I am using WinSCP 3.6.8 Build 245 on Windows XP Professional (with pretty much default settings). Recently I started seeing error messages after I click on a right-panel Refresh button (for a remote UNIX server): Error listing directory, Invalid access to memory, Invalid access to memory... I do not see them every time I click Refresh, just sometimes. I think that the error can happen only after some idle time (idle for WinSCP, not for me). When it happens, the right panel shows the standard animated light.
I made a screenshot that I can send to you if you like.