I've seen reports of OS "focus" issues, and this may or may not be related. My issue is similar to the one discussed here: http://forum.parallels.com/printthread.php?t=104426 I run Windows 7 32bit on Parallels version 6.0.11828 on my Snow Leopard MBP 13". When in coherence mode, the Windows start bar attempts to "surface" every 60 secs precisely, but only when a windows app or even windows explorer is "maximized". There is a half second jitter where the bottom or top of the screen flickers and then it happens again 60 seconds later. If in regular "window mode" I set the windows task bar to display at the top of the screen, and then switch back to coherence mode the flicker occurs at the top and bottom of the app's maximized window. If I set the task bar to display at the bottom of the screen, then the flicker only occurs at the bottom of the maximized app window. So I decided to set the Windows task bar to display on the left side of the screen and then went back into coherence mode. The flickering was gone. Not sure what caused the problem. But the flickering (may not be the same as the "focus" issue) is no longer visible.