Problem I encounter is rather hard to describe, so I provide a screenshot: http://dl.dropbox.com/u/1732760/video-distortion.png

As you can see there are some horizontal stripes in random colors. These stripes appear sometimes in all windowed apps, games and on the desktop too. They tend to stay in place until I refresh window (or force it to to redraw by for example minimizing and maximizing again). They also tend to appear in the same place and shape multiple times, even if they disappear, it's very likely they will be again in the same place after a while.

These artifacts do not blink or change if computer is idling. If I don't touch anything, do not use mouse, they will stay in place forever (unless some app redraws its window on its own).

I first encountered this problem some weeks ago. Back then I thought it might be cooling problem, so I took out the graphics card, removed dust from the radiator and fan and put it into PC back. I also ran some stress test using Furmark (peak tempearature was ~65C) to see if the problem becomes more intense if the card gets hotter, but suprisingly no artifacts whatsoever appear during the stress test.

Graphic card is Galaxy GeForce 7300 GT with DDR3 memory, was never overclocked. Drivers are the latest, from Nvidia site.

OS is Windows 7 64-bit, updated. AMD64 3000+, 2GB RAM.

I'm running a dual monitor setup with 2 19'' Samsung LCDs and problem is on both, so I assume it's not a monitor or cable issue.