Radeon 6950 - Garbling of text and graphics in certain Windows only

This morning I noticed the text in Gmail (in Firefox 4) looked a little funny (kind of thin, maybe some color fringing). I went to work and thought it might be some ClearType issue or something with the way Direct way that FF4 draws to the screen. When I came back from work (I left the computer on), the problem was much worse - way beyond ClearType nit-picking. The text was barely readable.

I opened Chrome and there was no such problem. It seems like only Windows that use hardware acceleration are garbled, and ones that use GDI are not. But, I fired up Dragon Age and didn't notice any problems (I only really looked at the main menu though).

Here is a link to a screen shot that illustrates the problem. Notice how the Windows Live Mesh window is completely unreadable, the text in Firefox 4 (left) is pretty bad, while Chrome, the Windows Control Panel, and the task bar are perfectly fine.

The fact that the problem shows up in screen shots and that it only happens in certain Windows makes me confident that the problem cannot be with the monitor or DVI cable.

I am using the AMD Radeon drivers from 4/27/11. The card I have (MSI Frozr II) came with a slight overclock (810Mhz) out of the box, but it looks like when I'm on the Windows desktop it's not running at full clock (CCC reports 450Mhz). Still, I underclocked it to the stock reference clock (800Mhz) and it made no difference. The idle temperature according to Afterburner is 42-44 Celsius, which seems a tad high but not enough to cause a problem - it's cold to the touch if I open up the machine.

What the heck could be causing this? The problem varies in intensity. As we speak I'm in Firefox and things look better than they did earlier - it'll probably get worse again soon.

Radeon 6950 (MSI Frozr II), Seasonic X 560, Core i5 2500K at stock clockspeeds, 16GB RAM, Asus P8P67 M Pro

Answer

From http://hardforum.com/showthread.php?p=1037183406 :

"Looks like you have Morphological AA enabled in the drivers. Firefox now hardware accelerates all 2D rendering so MLAA will blur the hell out of everything."

The screenshot there looks similar to part of your screenshot.