Symptom: transparent shutdown menu

[seanspotatobiz]

After running for a little while (eight hours or so), my computer develops problems with displaying webpages in both Firefox and IE and sometimes folders in Windows Explorer. The symptoms vary, but usually involve the background getting all messed up and repeating if I start scrolling on my mouse wheel, particularly if I do it quickly. One clear symptom is the transparent shut down menu: http://www.petaimg.com/uploads/1222607776.jpg

Windows was recently reinstalled but the problem continues.