Do you know what the virus is or how you got it? How do you know it was a virus and not some other error? How did you get rid of it or fix it?
Viruses very often can edit antivirus software so they can not be detected.
When that happens it can be hard to get rid of them. Antivirus programs are primarily designed to be ran before hand and protect you from getting infected, not ran after you are already infected. Here are some ways to try to get rid of a virus..
1. Online anti virus
HouseCall - Free Online Virus Scan - Trend Micro USA < if you suspect you have a problem that you r antivirus is not catching then use this and or the next one.
2. Boot CD Antivirus
Hirens Boot CD 10.4 (download torrent) - TPB < Very powerful, you can break your computer if you don't know what you are doing. But it can also bring it back from death if you do know what you are doing.
3. Free anti virus
avast! Free Antivirus - Download Software for Virus Protection < if you can't get something better use this.
4. Top of the line paid antivirus
Trial versions - G Data Software AG < this is what I use. It is very good protection but it slows my computer down some.
5. Windows comes with Windows Defender. It is very good for a free program. Use it but also use something above.