Trojan limewire help

Hello,

I recently accidentally downloaded a virus from Limewire in the form a song and now every minute Auto-Protect Results pops up telling me that there's a Trojan (Trojan.Brisv.A!inf to be exact) and it was Left Alone, because Quarantine failed and Clean failed. What should I do?? I tried deleting the song file but won't the virus technically still be on my computer? I can't get rid of the Auto-Protect window- it keeps coming back, even when I restart my computer! Its so annoying. Please help if you know anything.

Ps. I ran my Symantic Antivirus Live Update. It doesnt do anything. I've also ran the antivirus in safe mode with the system restore off and NOTHING works!!! Please HELP!