I had a problem with my computer always freezing during a quick scan at the point 'Scanning for Traces of: SecurityRisk.URLRedir'. I tried everything to resolve this including all of the tips at the various Norton forum discussions. I verified through multiple processes that my machine did not have a virus and felt exasperated. Note that when my computer would freeze, it would also block the channel in my router for the other computer in the same room on the same router channel. In the end, I thought about the 'Redirect' command and felt it might be a firewall issue. I went into the Control Panel and selected the Firewall configuration icon. I reselected Windows (turned on) the Windows Firewall which was previously being controled by Norton. My Quick Scan ran right through the scan, resolved one small isuue and all works well.
I am guessing that a firewall update from Microsoft (e.g., SP3) tried to change a process that was conflicting with the Norton control of the firewall. I am also guessing that returning the control to Norton may very well work well again at this point. Note that other symptoms during this period also included the computer freezing at other random times, but all when I was interacting over my network.
Anyway, I hope this post may help others with the same problem. Let me know.