Is my computer attacking itself!?!?

I just got a pop-up from Norton Antivirus saying "An intrusion attempt by CEC-PC was blocked" (CEC-PC is my computer name, but the attacking computer "CEC-PC" doesnt have the same ip address as my computer) The attack attempt was blocked but i dont know how to get rid of the virus.  Ive tried using NPE and that didnt find anything. The details to Nortons message is:

Risk Name: HTTP Suspicious Redirect Request 4
Attacking computer: CEC-PC (192.168.....(NOT MY IP))
Attacker URL: 173.224...../s/in.cgi?7&parameter=east&ur=1&HTTP_REFERER=adgear.com

Network traffic from CEC-PC matches the signature of a known attack. The attack was resulted from \DEVICE\HARDDISKVOLUME1\PROGRAM FILES\MOZILLA FIREFOX\FIREFOX.EXE. Network traffic from 173.224........./s/in.cgi?7&parameter=east&ur=1&HTTP_REFERER=adgear.com matches the signature of an unknown attack