Fixing my instant messaging?

Ever since I told my virus protection to delete all the infected files from the latest virus attack on me, I have had trouble connecting on AIM and MSN messengers. I need some help on what to do to make it work again. I tried reinstalling MSN messenger, but it still doesn't work. I haven't tried with the AIM messenger(I just figured it had the same problem). Yahoo instant messaging is unaffected. So I need to know what I can do to get this fixed.