Check for malicious software, do AV scans with an updated scanner and make sure theres no spyware on your system with MS Antispyware, Spybot or Ad-aware.
i wouldnt advise downloading AIM, rather try out aim express but you'll have to temporarily disable popup blocking on a firefox browser, AIM has files that change your computer settings, once it screws something up its a ***** to fix it, Wild tangeant is one of those programs, and its often caught by spybot s&d but deleting it makes things worse, id recommend uninstalling through add/remove programs and just using aimexpress from www.aim.com