Post a dxdiag.
XP: Go to Start->run, type “dxdiag” and hit enter. Click the Save All Information button near the bottom right. This will save a Dxdiag.txt in C:\ by default. Then open the dxdiag.txt and copy/paste the information into your post.
VISTA/Windows 7: Go to Start->Search, type “dxdiag” and hit enter, click the Save All Information button near the bottom right. This will save a Dxdiag.txt in C:\ by default. Then open the dxdiag.txt and copy/paste the information into your post.