Desktop resolution incorrect on exit of Windows

After I shutdown Windows, the cube effect gets triggered and the desktop of monitor 1 gets displayed on two monitors incorrectly. The text of the few icons that display is very large so it looks like the resolution of monitor 1 is set too high and spans to monitor 3. I can no longer access the command bar at the top nor the dock on the main monitor. The only way to get back control is turn the power off the computer and power back on. This is a sporadic issue although it happens about 50% of the time.

I am using Parallels Desktop for Mac, Build 4560. My hardware config is Mac Pro with three CinemaDisplays (one 30" and two 23"). My guest OS was Windows XP and I had the issue then. I recently upgraded to Windows Vista and I get the same problem.

I did not have this problem prior to the recent upgrades from the last two weeks.

Any ideas what could be wrong?

 

How much ram did you gave vm?

You can try reducing it.

 

I allocated 512MB. I'm under the impression that Windows Vista would need at least that much. Do you have a suggestion for how much to allocate?

 

and video memory is 16mb

 

When your mac has 2 gb on board, i should install at least 700 to 1 gb.