This bug has been a problem for me since 4191. It seems particularly bad for TNT2 cards (I have a TNT2/M64). I would get it when displaying large images in Mozilla (whether scaled down with height and width tags or not) and sometimes when using gv and zooming in a lot. I could kill the X server remotely, and restart but the text mode virtual terminals would be permanently messed up until reboot...
For this reason, I've been using build 3123, which pretty much does what I need it to and doesn't have any stability problems. It's odd that this bug has been outstanding for over a year now, without any fix or mention of it in the errata... Several months ago, it was posted on the boards that nvidia had reproduced it, but it never made it into the list of things to fix. It may only affect old cards, though, that don't need the new features in the 4xxx versions anyway. Is anyone having this kind of problems with more recent cards?