There is a new virus spreading through P2P applications and IM. Details here. This looks like a particularly unpleasant one.
If you practice my 2 second safety rule, you should be fine:
So let me introduce "Jeff’s 2 second safety tip" — Never open a file or link you receive in IM unless you can answer two questions about the file. "What is this?" and "Why did you send it?".
Stay safe out there.
Don’t click on any of the following files, it no matter who sends them to you: