<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)>
I came back to WinSCP this morning, and a few of my sessions had expired.  Instead of getting a "reconnect" on the second or third one, I got this.
WinSCP 5.6.1
Error message:
Invalid access to memory.
Stack trace:
[008B5F20] 
[7733C84E] ntdll.dll
[7733C6B6] ntdll.dll.KiUserExceptionDispatcher
[00214C4D] 
[00214CF0] 
[0057D708] 
[00365499] 
[0053B690] 
[76E07831] USER32.DLL.CallNextHookEx
[76E07A95] USER32.DLL
[76E09889] USER32.DLL
[76E098EC] USER32.DLL.DispatchMessageW