Erasing old posts.
I can try to get the same symptoms on my PC later (disable aero/try different themes, maybe).
Updating graphics drivers (and DirectX?) might help. Have you tested with different themes?
I don't know if this is your problem, although with some graphics/display cards it can be caused by buggy display drivers.
Erasing old posts.
Start in Windows Safe Mode, then if those black artifacts all of a sudden disappear it may be the graphics drivers. Well that's a simple of enough test without needlessly uninstalling and installing newer graphics drivers if that isn't the cause.