I've been having an issue with colored pixels ruining the visible screen.
Here are two pictures, where the error is white pixels in one and black in the other -
The old black is hardly noticeable so I ignored it, but the first picture is very annoying.
I've checked that my graphic card drivers are up to date (Radeon HD 6970), and the error persists with all addons disabled.
Help! I have no clue what the problem could be, as it only exists in WoW. Every other game runs fine, any ideas?
Looks just like the pattern that you got with heat damage to a Radeon chipset back in the days when they had bad solder on them. Because it was heat and thermal stress related it usually showed up first in some-but-not-all games that happened to stress the right stuff.
Beyond that, try bisecting your addons: turn off half of them, see if it happens. Cut the offending set in half until you find the one addon that breaks it (or the pair, or whatever.)