The Yahoo! Messenger on this computer in an internet cafe is infected... what can i do to clean it?

The YM installed here is the latest version but apparently someone else surfed in a porn site and brought a virus into this computer. Not only is the YM infected, but the IE also has a browser hijacker that automatically loads www.mytermex.com upon activating IE (happens as well even after i set the home page to yahoo.com). The YM is infected such that something triggers it to automatically send a malicious message to everyone on my YM (i think it occurs every 5 minutes). That's why i just created my own mesage and said that "if you see any malicious mesage, pls ignore it because the YM here is infected."

How can i clean or remove the virus/spyware without reformatting the cpu, since i've tried AVG antivirus and antispyware and even ad-aware and it is still here?

Thanks in advance! ^_^

The Yahoo! Messenger on this computer in an internet cafe is infected... what can i do to clean it?computer repair

there are so many worms that target yahoo messenger at the moment, most will send out random IM's to your friends with urls, or change your current status message along with a clickable url, you will need to clearly identify which one you have acquired and it's quite a mission to work this out as currently installed virus scanners are often a target (being disabled by the worm) so a clean bill of health from your antivirus program might in fact be incorrect. If you suspect this is the case online scanner (temporarily disable your currently installed one first though)...