Here's some fun error messages and stuff i've seen at work. Have fun laughing. I sure did. Until i remembered I was the one that had to fix them.

worlds most useful error message son of worlds most useful error message

This one is 800x600 so i'll link to it rather than stick it right in here.
Windows Minutes

Everyone has seen this one at least once, taken when Unreal Tournament crashed in win98:
Critical Error