If you have seen strange behavior with the Vista GUI, you might want to apply this hotfix.....
After a Windows Vista-based computer has been running for an extended period of time, the desktop screen may stop updating correctly. For example, you may experience any of the following symptoms:
* Parts of the screen may go black
* Parts of the screen may become transparent.
* The toolbar may disappear.
* The toolbar may appear at the top of the screen instead of at the bottom of the screen.
The Windows desktop may stop updating correctly after a Windows Vista-based computer has been running for an extended period of time