Something similar happened to me once not long ago.
The thing is, while trying to remove the 'virus' it deleted some important file. I had to use System Restore after turning off my computer and initiating in Safe Mode.
I recommend you try using AVG Anti-Spyware (previously ewido) aswell.
Try using System Restore, it worked wonders for me.
Ps: After restoring, scan with AVG Anti-Virus and Anti-Spyware and use Microsoft's Online OneCare Full Service Scan (Long name, yes) Here's the link
Edit: woops, didnt see you already fixed the problem. I wouldnt reccomend going back to Norton though, AVG is way better.