Invalid access to memory

Using WinSCP version 4.39 (Build 1817) running through Wine on Linux Mint 13 KDE.
After setting up a custom command and trying to save command, I get a window pop up that states "Invalid access to memory" and only option is to click 'OK'. On clicking, the same message pop up 2-3 times before going away. Also, closing down WinSCP and opening it again, the custom command has to be rentered.

Any ideas what's going on or anything I should try.

Thanks for any input.

Please try to upgrade to WinSCP 5.1.

Same problem after upgrading

Thanks for your report.
I have sent you an email with a debug version of WinSCP to address you have used to register on this forum.