Graphics issue when using Classic theme

Hi,
I recently installed the full version of windows 7 professional onto my computer. I have a Geforce 6600 plugged into my Panasonic Viera 720p TV through the use of a DVI-HDMI cable. I encounter some graphical issues at certain events when I use my system. First off, my login screen shows alot of random lines that are not supposed to be there, and when i type my password it the text box's contents are very pixely and messed up.

This problem also appears in other places. When trying to do administrative actions this error happens when the administrative prompt splash screen comes up. The buttons and surrounding space on the screen are very messed up, and if i move the prompt window it makes it worse. Though once i leave the prompt my screen goes back to working perfectly.

The last place I have gotten this error to reproduce at was when I switched my theme to the classic "old" windows theme. When running this theme almost everything gets messed up. Text on screen becomes illegible and if i move something the screen becomes even more messed up.

I'd like to point out, if I didn't already, that this only happens when windows is not running Aero, or when an overlay replaces Aero (like the admin prompt). I assume that the login screen does not run Aero, and that is also why it appears wrong.

Has anyone else encountered this problem? I find it very odd that I have graphics issues when displaying non-Aero items. Unfortunately I cannot post a screencap because the actual pictures only show what "should" be displayed on screen, and does not show the pixelation and lines.

Since you say it does not happen to Aero, this might help you. Aero is pretty most done on the Graphics Card, while everything else is done on the CPU.