I am using WinSCP v4.1.5 build 410 on a Windows XP SP2 PC.
When I select Tools... and then Check For Updates... the whole WinScp screen flickers once. Then the next time I repeat the procedure, no flicker. In previous versions of WinSCP I did not see this problem.
Also, after I log into my SFTP site, the WinScp screen dissapears for a short while before the files menu is shown. I hear my CD in my CDROM drive start up at this time too...