Please upgrade. You are using an old version of WinSCP.
The following error message is displayed when logging is enabled and the connection to the server host is being closed:
Assertion failed: (LogMemo->Parent == this) && (LogMemo->OnChange == LogMemoChange), file C:\Martin\Projekty\WinSCP2\forms\units\Log.cpp, line 77
It was quite interesting situation when I've resized the log window to maximally fit the screen this error has not been occured.
The log file contains the following regarding this incident:
. Startup conversation with host (shell) finished.
* (EAccessViolation) EAccessViolation
. Closing connection.
WinSCP2 is great!