Problem with Adium - people getting spam messages from me!

I've had Adium since I got my first mac (since Windows Messenger doesn't work properly). Lately I've been getting messages from my contacts that I'm spamming them with messages like this:

"I just found the coolest site, free and full of the best movies to watch www.forbestmovie.com"

Why is this happening? I'm pretty sure I don't have virus on my mac, is it something with the Adium/MSN? How do I remove it?

A few months ago I also got a lot of friend requests from totally strangers (with really weird email addresses), does it have something to do with this? I never accepted any of them, I blocked all of them.