Wavy blue lines during PC crash

I am not tech savvy at all so hopefully you all can stick with me through this post....

Tonight I had my PC crash for twice while playing random games on it. Crashing is not a normal thing for me at all so I am somewhat concerned as to why it is happening. Basically my screen would freeze, but across it there would be tiny wavy blue lines.

Some possibly helpful info: * 64 bit windows 7 * Nvidia GeForce 9800 GT * Was using Dual monitors at the time * Video Drivers were updated 4/7/2011 (downloading the updates now because I assume that will need to be done regardless of what the issue is)

Can't think of anything else that is important, but I probably missed something super vital.