I have a 2008 Intel iMac running Windows 7 through Boot Camp. I am seeing some weird display behaviors in Windows 7 that I can't explain or seem to fix. There are diagonal lines that move across the screen from right to left. There seems to be some distortion on certain images. For example sometimes areas of the screen will suffer from visual degradation similar to what you see with JPEG compression on the web. Certain colors and patterns appear to produce the effect more than others.
The graphics card is the ATI Mobility Radeon HD 2400 XT.
I doubt it's a hardware issue because it doesn't happen in OS X. It also didn't happen in Windows XP.
If I have downloaded all the latest drivers per Boot Camp's recommendations. I have been on the phone with Apple support and they have basically told me that they won't help since it only happens in Windows and not OS X (despite the fact that I still have a year left on my Apple Care).
I tried contacting AMD, who apparently not owns ATI, and they basically refused to help as well. Actually, they told me that they recommend I use the Boot Camp drivers but that if I did that they wouldn't support me. Jackasses.
If I manually update the ATI drivers the problem immediately goes away, but as soon as I reboot, log off, or even lock the computer, it comes right back.
Does anyone have any ideas about what I can do? Apparently nobody wants to take responsibility for this issue.