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.

<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 5.17.6

Error message:
メモリのアクセス違反

スタック トレース:
(00279157) Vcl::Controls::TWinControl::UpdateShowing
(00F87E4E) C5296_0
(00F89EB6) ____ExceptionHandler
(00F86C70) __ExceptionHandler
(00087E3F) ntdll.dll
(000732D1) ntdll.dll.KiUserExceptionDispatcher
(002791EA) Vcl::Controls::TWinControl::UpdateShowing
(00279364) Vcl::Controls::TWinControl::UpdateControlState
(0027BF0A) Vcl::Controls::TWinControl::CMVisibleChanged
(00279E65) Vcl::Controls::TWinControl::WndProc
(0023432C) Vcl::Forms::TCustomForm::WndProc

(0027CB48) Vcl::Controls::TWinControl::CMInvalidate
(00087E3F) ntdll.dll
(000732D1) ntdll.dll.KiUserExceptionDispatcher
(00279E65) Vcl::Controls::TWinControl::WndProc
(0023432C) Vcl::Forms::TCustomForm::WndProc

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.