Invalid access to memory

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WinSCP 6.1.1

Error message:
Invalid access to memory.

Stack trace:
(0029466B)
(00087AEF) ntdll.dll
(00073FB1) ntdll.dll.KiUserExceptionDispatcher
(00214D98)
(00040379) USER32.dll
(00037345) USER32.dll
(000350B5) USER32.dll
(00034E7B) USER32.dll.DispatchMessageW

(00294258)
(00087AEF) ntdll.dll
(00073FB1) ntdll.dll.KiUserExceptionDispatcher
(00214D98)
(00040379) USER32.dll
(00037345) USER32.dll
(000350B5) USER32.dll
(00034E7B) USER32.dll.DispatchMessageW

Status: unknown_rel_addr

The problem happens rarely. I cannot reproduce it.