I just got a very odd error using my MacBook Pro with Mac OS X Snow Leopard 10.6
I was in Firefox 6.0, trying to enter info in a web form, and a transparent black curtain came down from the top to the bottom of the screen. Then a message popup that said,
You need to restart you computer. Hold down the power button until the computer turns off...
I think I've seen this once before a while ago.
Are there any common causes for this dramatic crash?