@olegs18: 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.

I'm running it on Arch Linux via Wine, and error windows pop up at startup. I close them, and everything is fine after that.
https://www.awesomescreenshot.com/image/63452294?key=9bbeed559fc1456a4af2a50001a43aed

WinSCP 6.5.7

Error message:
Invalid access to memory.

Stack trace:
(00025818)
(0000D4FE)ntdll.dll
(0004EFDB)ntdll.dll
(00051578)ntdll.dll
(0000D354)ntdll.dll
(00025AA4)
(00402209)
(003A356D)
(0039DFF8)
(003A36C7)
(0039E3C2)
(003A356D)
(004A77B4)
(00E0808B)
(003A2A78)
(00204C90)
(00009646) user32.dll.GetWindowLongA
(000616D2) user32.dll
(000677F5) user32.dll
(00053313) user32.dll
(00051A5E)ntdll.dll
(000111CA)ntdll.dll
(00010BE6) win32u.dll.NtUserMessageCall
(0008522A) comctl32.dll
(00086519) comctl32.dll
(00009646) user32.dll.GetWindowLongA
(000616D2) user32.dll
(000677F5) user32.dll
(0000F9BF) user32.dll.CallWindowProcW
(003A3675)
(003A356D)
(003A2A78)
(00204C90)
(00009646) user32.dll.GetWindowLongA
(000616D2) user32.dll
(000677F5) user32.dll
(0000F9BF) user32.dll.CallWindowProcW
(00539473)
(00204C90)
(00009646) user32.dll.GetWindowLongA
(000616D2) user32.dll
(000677F5) user32.dll
(00053313) user32.dll
(00051A5E)ntdll.dll
(000111CA)ntdll.dll
(00010BE6) win32u.dll.NtUserMessageCall
(0016B30F)
(00401F18)
(001EE49F)
(00404117)
(00403682)

Status: unknown_rel_addr

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.