Things like that are extremely annoying. Even though it does cost a little, one really should have his/her computer really well protected. It pays off in the end. Norton anti-virus or F-Secure internet security are the best, or so I'm told. I've got F-secure and it works like a charm. You know, you can go to
Antivirus Software and Internet Security Tools - F-Secure and there's a search box. You can write the name of the virus/worm/trojan and there are usually instructions on how to remove them manually.