<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 6.3.4

Error message:
Invalid access to memory.

Stack trace:
(002A731F) System::DoneExcept
(00098CCF) ntdll.dll
(000781E1) ntdll.dll.KiUserExceptionDispatcher
(00226F2C) System::Classes::_18201
(000326D1) USER32.dll
(000234E1) USER32.dll
(00022E52) USER32.dll.CallWindowProcW
(0007F354) COMCTL32.DLL
(0007F3F3) COMCTL32.DLL
(0007F16C) COMCTL32.DLL
(000326D1) USER32.dll
(000234E1) USER32.dll
(00022E52) USER32.dll.CallWindowProcW
(004C2CEB) Dragdrop::TDragDrop::WndMethod
(00226F2C) System::Classes::_18201
(000326D1) USER32.dll
(000234E1) USER32.dll
(00021DA0) USER32.dll
(000218EB) USER32.dll.DispatchMessageW

(002A6F0C) System::HandleAnyException
(00098CCF) ntdll.dll
(000781E1) ntdll.dll.KiUserExceptionDispatcher
(00226F2C) System::Classes::_18201
(000326D1) USER32.dll
(000234E1) USER32.dll
(00022E52) USER32.dll.CallWindowProcW
(0007F354) COMCTL32.DLL
(0007F3F3) COMCTL32.DLL
(0007F16C) COMCTL32.DLL
(000326D1) USER32.dll
(000234E1) USER32.dll
(00022E52) USER32.dll.CallWindowProcW
(004C2CEB) Dragdrop::TDragDrop::WndMethod
(00226F2C) System::Classes::_18201
(000326D1) USER32.dll
(000234E1) USER32.dll
(00021DA0) USER32.dll
(000218EB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 6.3.3

Error message:
Invalid access to memory.

Stack trace:
(002A761F) System::DoneExcept
(0009823F) ntdll.dll
(00077E51) ntdll.dll.KiUserExceptionDispatcher
(002271BC) System::Classes::_18201
(000320B1) USER32.dll
(00022EF1) USER32.dll
(00022862) USER32.dll.CallWindowProcW
(0007F334) COMCTL32.DLL
(0007F3D3) COMCTL32.DLL
(0007F14C) COMCTL32.DLL
(000320B1) USER32.dll
(00022EF1) USER32.dll
(00022862) USER32.dll.CallWindowProcW
(004C32DF) Dragdrop::TDragDrop::WndMethod
(002271BC) System::Classes::_18201
(000320B1) USER32.dll
(00022EF1) USER32.dll
(000217B0) USER32.dll
(000212FB) USER32.dll.DispatchMessageW

(002A720C) System::HandleAnyException
(0009823F) ntdll.dll
(00077E51) ntdll.dll.KiUserExceptionDispatcher
(002271BC) System::Classes::_18201
(000320B1) USER32.dll
(00022EF1) USER32.dll
(00022862) USER32.dll.CallWindowProcW
(0007F334) COMCTL32.DLL
(0007F3D3) COMCTL32.DLL
(0007F14C) COMCTL32.DLL
(000320B1) USER32.dll
(00022EF1) USER32.dll
(00022862) USER32.dll.CallWindowProcW
(004C32DF) Dragdrop::TDragDrop::WndMethod
(002271BC) System::Classes::_18201
(000320B1) USER32.dll
(00022EF1) USER32.dll
(000217B0) USER32.dll
(000212FB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.21.7

Error message:
Invalid access to memory.

Stack trace:
(0043D33F) System::DoneExcept
(000974CF) ntdll.dll
(00077751) ntdll.dll.KiUserExceptionDispatcher
(003C9C40) System::Classes::_18201
(000313E1) USER32.dll
(000220E1) USER32.dll
(00021A52) USER32.dll.CallWindowProcW
(004A18FF) Dragdrop::TDragDrop::WndMethod
(003C9C40) System::Classes::_18201
(000313E1) USER32.dll
(000220E1) USER32.dll
(000209A0) USER32.dll
(000204EB) USER32.dll.DispatchMessageW

(0043CF2C) System::HandleAnyException
(000974CF) ntdll.dll
(00077751) ntdll.dll.KiUserExceptionDispatcher
(003C9C40) System::Classes::_18201
(000313E1) USER32.dll
(000220E1) USER32.dll
(00021A52) USER32.dll.CallWindowProcW
(004A18FF) Dragdrop::TDragDrop::WndMethod
(003C9C40) System::Classes::_18201
(000313E1) USER32.dll
(000220E1) USER32.dll
(000209A0) USER32.dll
(000204EB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.17.9

Error message:
Acceso a memoria no válido

Traza de la pila:
(00419487) System::DoneExcept
(00088F2F) ntdll.dll
(000743C1) ntdll.dll.KiUserExceptionDispatcher
(003A5954) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000237FA) USER32.dll.CallWindowProcW
(00076417) COMCTL32.DLL
(000764B6) COMCTL32.DLL
(000761CC) COMCTL32.DLL
(000437A9) USER32.dll
(000242A7) USER32.dll
(000237FA) USER32.dll.CallWindowProcW
(0047CC8B) Dragdrop::TDragDrop::WndMethod
(003A5954) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000233F9) USER32.dll
(000231DB) USER32.dll.DispatchMessageW

(00419074) System::HandleAnyException
(00088F2F) ntdll.dll
(000743C1) ntdll.dll.KiUserExceptionDispatcher
(003A5954) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000237FA) USER32.dll.CallWindowProcW
(00076417) COMCTL32.DLL
(000764B6) COMCTL32.DLL
(000761CC) COMCTL32.DLL
(000437A9) USER32.dll
(000242A7) USER32.dll
(000237FA) USER32.dll.CallWindowProcW
(0047CC8B) Dragdrop::TDragDrop::WndMethod
(003A5954) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000233F9) USER32.dll
(000231DB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.13.9

Error message:
Invalid access to memory.

Stack trace:
(003F2CF7) System::DoneExcept
(00087D6F) ntdll.dll
(00073211) ntdll.dll.KiUserExceptionDispatcher
(00381138) System::Classes::_18201
(000436C9) USER32.dll
(000250B7) USER32.dll
(0002460A) USER32.dll.CallWindowProcW
(000756A7) COMCTL32.DLL
(00075746) COMCTL32.DLL
(0007545C) COMCTL32.DLL
(000436C9) USER32.dll
(000250B7) USER32.dll
(0002460A) USER32.dll.CallWindowProcW
(00444093) Dragdrop::TDragDrop::WndMethod
(00381138) System::Classes::_18201
(000436C9) USER32.dll
(000250B7) USER32.dll
(00024209) USER32.dll
(00023FCB) USER32.dll.DispatchMessageW

(003F28E4) System::HandleAnyException
(00087D6F) ntdll.dll
(00073211) ntdll.dll.KiUserExceptionDispatcher
(00381138) System::Classes::_18201
(000436C9) USER32.dll
(000250B7) USER32.dll
(0002460A) USER32.dll.CallWindowProcW
(000756A7) COMCTL32.DLL
(00075746) COMCTL32.DLL
(0007545C) COMCTL32.DLL
(000436C9) USER32.dll
(000250B7) USER32.dll
(0002460A) USER32.dll.CallWindowProcW
(00444093) Dragdrop::TDragDrop::WndMethod
(00381138) System::Classes::_18201
(000436C9) USER32.dll
(000250B7) USER32.dll
(00024209) USER32.dll
(00023FCB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

Conditions:
WinSCP.com or WinSCP.exe. Ver: 5.13.3
Binary transfer via sFTP of 303 MB file.
Using -rawsettings TryAgent=0 AuthKI=0 RekeyBytes=0

Error message:
Invalid access to memory.

Stack trace:
. 2018-11-16 08:23:10.080 Checking existence of partially transferred file.
> 2018-11-16 08:23:10.080 Type: SSH_FXP_LSTAT, Size: 62, Number: 8122119
< 2018-11-16 08:23:10.084 Type: SSH_FXP_STATUS, Size: 95, Number: 8122119
< 2018-11-16 08:23:10.084 Status code: 2
. 2018-11-16 08:23:10.084 Opening remote file.
> 2018-11-16 08:23:10.084 Type: SSH_FXP_OPEN, Size: 78, Number: 8122371
< 2018-11-16 08:23:10.094 Type: SSH_FXP_HANDLE, Size: 45, Number: 8122371
> 2018-11-16 08:23:10.094 Type: SSH_FXP_WRITE, Size: 32764, Number: 8122886
. 2018-11-16 08:23:11.190 Server initiated key re-exchange
. 2018-11-16 08:23:11.190 Doing Diffie-Hellman group exchange
. 2018-11-16 08:23:11.750 10685 skipped SSH_FXP_WRITE, SSH_FXP_READ, SSH_FXP_DATA and SSH_FXP_STATUS packets.
> 2018-11-16 08:23:11.750 Type: SSH_FXP_CLOSE, Size: 45, Number: 10582788
. 2018-11-16 08:23:12.487 Doing Diffie-Hellman key exchange with hash SHA-256
. 2018-11-16 08:23:16.442 Initialised AES-256 CBC client->server encryption
. 2018-11-16 08:23:16.442 Initialised HMAC-SHA-256 client->server MAC algorithm
. 2018-11-16 08:23:22.628 expected key exchange reply packet from server
. 2018-11-16 08:23:22.628 Fatal error while disposing the SFTP queue.
. 2018-11-16 08:23:22.628 Connection was lost, asking what to do.
. 2018-11-16 08:23:22.628 Asking user:
. 2018-11-16 08:23:22.628 expected key exchange reply packet from server ()
< 2018-11-16 08:23:22.628 Script: expected key exchange reply packet from server
. 2018-11-16 08:23:26.823 Connection was lost, asking what to do.
. 2018-11-16 08:23:26.824 Asking user:
. 2018-11-16 08:23:26.824 Invalid access to memory.
. 2018-11-16 08:23:26.824
. 2018-11-16 08:23:26.824 Please help us improving WinSCP by reporting the error on WinSCP support forum. ("Stack trace:","(003EE310) System::SysFreeMem","(008BCA5A) C5104_0","(008BEAC2) ____ExceptionHandler","(008BB87C) __ExceptionHandler","(0006248E) ntdll.dll","(0000F15E) ntdll.dll.KiUserExceptionDispatcher","(008AA413) ___org_free","(0063B31F) _safefree","(0063F09F) C2484_0","(0064FAD3) _sshfwd_x11_is_local","(0073752C) TSecureShell::FreeBackend","(007321FE) TSecureShell::Open","(0077CB37) TSFTPFileSystem::Open","(007B6C8B) TTerminal::Reopen","(007B90FD) TTerminal::QueryReopen","(007AFECD) TRobustOperationLoop::TryReopen","(007CF113) TTerminal::SourceRobust","(007CEF54) TTerminal::DoCopyToRemote","(007A04C2) TSFTPFileSystem::CopyToRemote","(007CE9B9) TTerminal::CopyToRemote","(00727F93) TScript::PutProc","(00722B3F) TScriptCommands::Execute","(00723F0E) TScript::Command","(0005601F) TConsoleRunner::Run","(0005C8B6) Console","(000E2042) Execute","(000024B4) wWinMain","(008BAA91) C4972_0","(00038830) ntdll.dll","(00038800) ntdll.dll",,"(008BD0C5) C5104_0","(008BE69F) _ReThrowException","(007B554D) TTerminal::Open","(007B6C8B) TTerminal::Reopen","(007B90FD) TTerminal::QueryReopen","(007AFECD) TRobustOperationLoop::TryReopen","(007CF113) TTerminal::SourceRobust","(007CEF54) TTerminal::DoCopyToRemote","(007A04C2) TSFTPFileSystem::CopyToRemote","(007CE9B9) TTerminal::CopyToRemote","(00727F93) TScript::PutProc","(00722B3F) TScriptCommands::Execute","(00723F0E) TScript::Command","(0005601F) TConsoleRunner::Run","(0005C8B6) Console","(000E2042) Execute","(000024B4) wWinMain","(008BAA91) C4972_0","(00038830) ntdll.dll","(00038800) ntdll.dll")
< 2018-11-16 08:23:26.824 Script: Invalid access to memory.
< 2018-11-16 08:23:26.824 Please help us improving WinSCP by reporting the error on WinSCP support forum.
< 2018-11-16 08:23:26.824 Script: Stack trace:

< 2018-11-16 08:23:26.824 (003EE310) System::SysFreeMem

< 2018-11-16 08:23:26.824 (008BCA5A) C5104_0

< 2018-11-16 08:23:26.824 (008BEAC2) ____ExceptionHandler

< 2018-11-16 08:23:26.824 (008BB87C) __ExceptionHandler

< 2018-11-16 08:23:26.824 (0006248E) ntdll.dll

< 2018-11-16 08:23:26.824 (0000F15E) ntdll.dll.KiUserExceptionDispatcher

< 2018-11-16 08:23:26.824 (008AA413) ___org_free

< 2018-11-16 08:23:26.824 (0063B31F) _safefree

< 2018-11-16 08:23:26.824 (0063F09F) C2484_0

< 2018-11-16 08:23:26.824 (0064FAD3) _sshfwd_x11_is_local

< 2018-11-16 08:23:26.824 (0073752C) TSecureShell::FreeBackend

< 2018-11-16 08:23:26.824 (007321FE) TSecureShell::Open

< 2018-11-16 08:23:26.824 (0077CB37) TSFTPFileSystem::Open

< 2018-11-16 08:23:26.824 (007B6C8B) TTerminal::Reopen

< 2018-11-16 08:23:26.824 (007B90FD) TTerminal::QueryReopen

< 2018-11-16 08:23:26.824 (007AFECD) TRobustOperationLoop::TryReopen

< 2018-11-16 08:23:26.824 (007CF113) TTerminal::SourceRobust

< 2018-11-16 08:23:26.824 (007CEF54) TTerminal::DoCopyToRemote

< 2018-11-16 08:23:26.824 (007A04C2) TSFTPFileSystem::CopyToRemote

< 2018-11-16 08:23:26.824 (007CE9B9) TTerminal::CopyToRemote

< 2018-11-16 08:23:26.824 (00727F93) TScript::PutProc

< 2018-11-16 08:23:26.824 (00722B3F) TScriptCommands::Execute

< 2018-11-16 08:23:26.824 (00723F0E) TScript::Command

< 2018-11-16 08:23:26.824 (0005601F) TConsoleRunner::Run

< 2018-11-16 08:23:26.824 (0005C8B6) Console

< 2018-11-16 08:23:26.824 (000E2042) Execute

< 2018-11-16 08:23:26.824 (000024B4) wWinMain

< 2018-11-16 08:23:26.824 (008BAA91) C4972_0

< 2018-11-16 08:23:26.824 (00038830) ntdll.dll

< 2018-11-16 08:23:26.824 (00038800) ntdll.dll

< 2018-11-16 08:23:26.824

< 2018-11-16 08:23:26.824 (008BD0C5) C5104_0

< 2018-11-16 08:23:26.824 (008BE69F) _ReThrowException

< 2018-11-16 08:23:26.824 (007B554D) TTerminal::Open

< 2018-11-16 08:23:26.824 (007B6C8B) TTerminal::Reopen

< 2018-11-16 08:23:26.824 (007B90FD) TTerminal::QueryReopen

< 2018-11-16 08:23:26.824 (007AFECD) TRobustOperationLoop::TryReopen

< 2018-11-16 08:23:26.824 (007CF113) TTerminal::SourceRobust

< 2018-11-16 08:23:26.824 (007CEF54) TTerminal::DoCopyToRemote

< 2018-11-16 08:23:26.824 (007A04C2) TSFTPFileSystem::CopyToRemote

< 2018-11-16 08:23:26.824 (007CE9B9) TTerminal::CopyToRemote

< 2018-11-16 08:23:26.824 (00727F93) TScript::PutProc

< 2018-11-16 08:23:26.824 (00722B3F) TScriptCommands::Execute

< 2018-11-16 08:23:26.824 (00723F0E) TScript::Command

< 2018-11-16 08:23:26.824 (0005601F) TConsoleRunner::Run

< 2018-11-16 08:23:26.824 (0005C8B6) Console

< 2018-11-16 08:23:26.824 (000E2042) Execute

< 2018-11-16 08:23:26.824 (000024B4) wWinMain

< 2018-11-16 08:23:26.824 (008BAA91) C4972_0

< 2018-11-16 08:23:26.824 (00038830) ntdll.dll

< 2018-11-16 08:23:26.824 (00038800) ntdll.dll
. 2018-11-16 08:23:29.439 Connection was lost, asking what to do.
. 2018-11-16 08:23:29.439 Asking user:
. 2018-11-16 08:23:29.439 Invalid access to memory.
. 2018-11-16 08:23:29.439
. 2018-11-16 08:23:29.439 Please help us improving WinSCP by reporting the error on WinSCP support forum. ("Stack trace:","(003EE327) System::SysFreeMem","(008BCA5A) C5104_0","(008BEAC2) ____ExceptionHandler","(008BB87C) __ExceptionHandler","(0006248E) ntdll.dll","(0000F15E) ntdll.dll.KiUserExceptionDispatcher","(008AA413) ___org_free","(0063B31F) _safefree","(0063F09F) C2484_0","(0064FAD3) _sshfwd_x11_is_local","(0073752C) TSecureShell::FreeBackend","(007321FE) TSecureShell::Open","(0077CB37) TSFTPFileSystem::Open","(007B6C8B) TTerminal::Reopen","(007B90FD) TTerminal::QueryReopen","(007AFECD) TRobustOperationLoop::TryReopen","(007CF113) TTerminal::SourceRobust","(007CEF54) TTerminal::DoCopyToRemote","(007A04C2) TSFTPFileSystem::CopyToRemote","(007CE9B9) TTerminal::CopyToRemote","(00727F93) TScript::PutProc","(00722B3F) TScriptCommands::Execute","(00723F0E) TScript::Command","(0005601F) TConsoleRunner::Run","(0005C8B6) Console","(000E2042) Execute","(000024B4) wWinMain","(008BAA91) C4972_0","(00038830) ntdll.dll","(00038800) ntdll.dll",,"(008BD0C5) C5104_0","(008BE69F) _ReThrowException","(007B554D) TTerminal::Open","(007B6C8B) TTerminal::Reopen","(007B90FD) TTerminal::QueryReopen","(007AFECD) TRobustOperationLoop::TryReopen","(007CF113) TTerminal::SourceRobust","(007CEF54) TTerminal::DoCopyToRemote","(007A04C2) TSFTPFileSystem::CopyToRemote","(007CE9B9) TTerminal::CopyToRemote","(00727F93) TScript::PutProc","(00722B3F) TScriptCommands::Execute","(00723F0E) TScript::Command","(0005601F) TConsoleRunner::Run","(0005C8B6) Console","(000E2042) Execute","(000024B4) wWinMain","(008BAA91) C4972_0","(00038830) ntdll.dll","(00038800) ntdll.dll")
< 2018-11-16 08:23:29.439 Script: Invalid access to memory.
< 2018-11-16 08:23:29.439 Please help us improving WinSCP by reporting the error on WinSCP support forum.
< 2018-11-16 08:23:29.442 Script: Stack trace:

< 2018-11-16 08:23:29.442 (003EE327) System::SysFreeMem

< 2018-11-16 08:23:29.442 (008BCA5A) C5104_0

< 2018-11-16 08:23:29.442 (008BEAC2) ____ExceptionHandler

< 2018-11-16 08:23:29.442 (008BB87C) __ExceptionHandler

< 2018-11-16 08:23:29.442 (0006248E) ntdll.dll

< 2018-11-16 08:23:29.442 (0000F15E) ntdll.dll.KiUserExceptionDispatcher

< 2018-11-16 08:23:29.442 (008AA413) ___org_free

< 2018-11-16 08:23:29.442 (0063B31F) _safefree

< 2018-11-16 08:23:29.442 (0063F09F) C2484_0

< 2018-11-16 08:23:29.442 (0064FAD3) _sshfwd_x11_is_local

< 2018-11-16 08:23:29.442 (0073752C) TSecureShell::FreeBackend

< 2018-11-16 08:23:29.442 (007321FE) TSecureShell::Open

< 2018-11-16 08:23:29.442 (0077CB37) TSFTPFileSystem::Open

< 2018-11-16 08:23:29.442 (007B6C8B) TTerminal::Reopen

< 2018-11-16 08:23:29.442 (007B90FD) TTerminal::QueryReopen

< 2018-11-16 08:23:29.442 (007AFECD) TRobustOperationLoop::TryReopen

< 2018-11-16 08:23:29.442 (007CF113) TTerminal::SourceRobust

< 2018-11-16 08:23:29.442 (007CEF54) TTerminal::DoCopyToRemote

< 2018-11-16 08:23:29.442 (007A04C2) TSFTPFileSystem::CopyToRemote

< 2018-11-16 08:23:29.442 (007CE9B9) TTerminal::CopyToRemote

< 2018-11-16 08:23:29.442 (00727F93) TScript::PutProc

< 2018-11-16 08:23:29.442 (00722B3F) TScriptCommands::Execute

< 2018-11-16 08:23:29.442 (00723F0E) TScript::Command

< 2018-11-16 08:23:29.442 (0005601F) TConsoleRunner::Run

< 2018-11-16 08:23:29.442 (0005C8B6) Console

< 2018-11-16 08:23:29.442 (000E2042) Execute

< 2018-11-16 08:23:29.442 (000024B4) wWinMain

< 2018-11-16 08:23:29.442 (008BAA91) C4972_0

< 2018-11-16 08:23:29.442 (00038830) ntdll.dll

< 2018-11-16 08:23:29.442 (00038800) ntdll.dll

I know how to reproduce the problem or the problem happens frequently enough. I wish to be contacted by the WinSCP team to help resolving the problem.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.7.6

Error message:
Error getting name of current remote directory.

Invalid access to memory.

Stack trace:
(003FF07D) Dragdrop::TDragDrop::WndMethod
(007E46BA) C4799_3
(007E6722) ____ExceptionHandler
(007E369C) __ExceptionHandler
(0008A63F) ntdll.dll
(00077E9A) ntdll.dll.KiUserExceptionDispatcher
(00713702) TTerminal::ReadCurrentDirectory
(0070F6B6) TTerminal::ReactOnCommand
(006154B7) TUnixDirView::ChangeDirectory
(00613902) TUnixDirView::ExecuteFile
(0021C315) Vcl::Controls::TWinControl::WndProc
(00260243) Vcl::Comctrls::TCustomListView::WndProc
(003402A8) System::Classes::_18201
(000374F1) USER32.dll
(00015C3B) USER32.dll
(000159D2) USER32.dll.CallWindowProcW
(00098CBA) COMCTL32.DLL
(00098CA1) COMCTL32.DLL
(00098ADC) COMCTL32.DLL
(000374F1) USER32.dll
(00015C3B) USER32.dll
(000159D2) USER32.dll.CallWindowProcW
(003FEE7F) Dragdrop::TDragDrop::WndMethod
(003402A8) System::Classes::_18201
(000374F1) USER32.dll
(00015C3B) USER32.dll
(0001553C) USER32.dll
(000152FB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.