Green and Purple lines. Not a screen problem.

The other night I was facebooking all of a sudden my computer made a click noise and 15 wide green and purple lines ran from the top to the bottom of my screen and my mac would be unresponsive to anything at all. I just turn my computer back on and the computer acts as if nothing happened. Not sure if anyone has an idea as to what has caused this or weather anyone has also experienced this. Cheers

First up pop in your system restore DVD and run Apple Hardware Test which does a check of graphics. Here is a link about this problem:-

Apple - Support - Discussions - Display leaves green and purple lines ...

This is a picture i took on my iphone of what the screen looks like.