I had a problem similar to this in a Digimate L1916D last year - flashing red pixels, loads of them, more than I had time to count. They would appear between certain colours. That meant if you loaded up an image in an art package, the flashing red pixels would follow the image around when you moved it. Very odd. It got worse the longer you left the screen on too, on first booting into windows it could be fine, but 10 minutes later the pixels would start to appear. Running games seemed to make it worse too.
It did only happen with the DVI though, not with VGA. It was reduced by using the 'alternate DVI mode' in the ATI CCC drivers and it was reduced even more by using 60 Hz instead of 75 Hz (IIRC), but it didn't go away completely. I ended up taking the monitor back (local shop) but they couldn't reproduce the problem (typical), so I assumed it was my video card, paid a restocking fee and bought something else.
With the new monitor though, no flashing pixels through DVI, comfirming my video card was 100% ok. I suspect the monitors electronics were faulty. It definitely wasn't video card artifacting btw or that would have showed up through both VGA and DVI, plus the cards temps were fine.