Invalid access to memory - Vcl::Extctrls::TTimer::WndProc

<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 5.13.2

Error message:
Invalid access to memory.

Stack trace:
(00231873) Vcl::Extctrls::TTimer::WndProc
(00088DEF) ntdll.dll
(0006FCE1) ntdll.dll.KiUserExceptionDispatcher
(0038022C) System::Classes::_18201
(0001D0B9) USER32.dll
(00027844) USER32.dll
(0002A140) USER32.dll
(000180D7) USER32.dll
(00017C1B) USER32.dll.DispatchMessageW

(003F19D8) System::HandleAnyException
(00088DEF) ntdll.dll
(0006FCE1) ntdll.dll.KiUserExceptionDispatcher
(0038022C) System::Classes::_18201
(0001D0B9) USER32.dll
(00027844) USER32.dll
(0002A140) USER32.dll
(000180D7) USER32.dll
(00017C1B) USER32.dll.DispatchMessageW

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.

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 6.5.6

Error message:
Invalid access to memory.

Stack trace:
(0044D59E) Vcl::Extctrls::TTimer::WndProc
(000B367F) ntdll.dll
(0007A5AA) ntdll.dll.KiUserExceptionDispatcher
(00204C90) System::Classes::_18364
(000387B1) USER32.dll
(000275A8) USER32.dll
(00026575) USER32.dll
(000260DB) USER32.dll.DispatchMessageW

(00138C18) System::HandleAnyException
(000B367F) ntdll.dll
(0007A5AA) ntdll.dll.KiUserExceptionDispatcher
(00204C90) System::Classes::_18364
(000387B1) USER32.dll
(000275A8) USER32.dll
(00026575) USER32.dll
(000260DB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.