Well, perhaps the computer is scared of your cat (or whatever pet you may have).... As Mr. K. (or is that Agent K. as in "MiB"?) said, we need more info...
Okay, I'm using After Effects CS4. I am on a Mac OSX 10.7.3
The message "Unepected Error" appears and is then followed by another window which says "After Effects can't continue: unexpected failure during application set up."
This all began when I was working on a project and left it for about an hour. When I came back to my computer AE had crashed and these are the messages I get when I try to re-start it.
I've recently switched computers and transfered all the software from the old one to this new one.
I used to have this same problem when I used AE on my old mac but deleted some files, I think 'Preferences', from the AE folder in Applications and this sorted the problem out.
'Preferences' don't appear in the AE folder on my new Mac.