"If you try to install and your computer has a virus, Norton AntiVirus requests that you restart your computer. Restart from the Norton AntiVirus CD and scan your computer's hard disk for viruses. The Norton AntiVirus emergency program uses the virus definitions from the Norton AntiVirus CD, and is not as up-to-date as virus definitions downloaded using LiveUpdate.
Once the virus has been repaired, delete the Norton AntiVirus install files in the temporary folder that are left behind after the forced shutdown."
Do you know how to boot your PC from the CD (if you do not post back) if you do this and you can run a Virus scan from the CD.