In case you have been living under a rock lately, Nvidia GPUs and chipsets have been crapping out at an amazingly high rate of speed. You can read about it here and here and here and here and here if you are really bored. The executive summary is that Nvidia has a massive batch of bad chips and the first ones to go bad are in laptops, but the problem is by no means confined to those machines.
I've been trumpeting about how bad Nvidia chipsets have been recently on here a lot. If you're building a new PC, STAY AWAY FROM Nforge CHIPSETS! Intel's stuff is so much better it isn't even funny. SLi isn't worth a crappy motherboard.