Is there a virus on my computer causing AIM to act weird?

when i am on AIM i lately have been getting random ims from my friends that say "i just posted some new pics on mebo, you should check it out, click the link" i never did but i decided to ignore it. then i kept getting more and more of these from different people on my buddy list, and today i got one from my friend and it said "i posted some hot nudes here log in to see" then a link. that is not like her to say that, and i think my aim has a virus. Help?