Norton is notoriously crappy in detection, You've ran superantispyware, (which I heard was good but I've never used it.. I've only used Lavasoft Ad-Aware + my AV) which detected and deleted but you still have the same problem.
Possibilities..
1. It might be a rootkit like brundle said.. I use Sophos anti-rootkit detector, it scans deep and find almost any hidden thing.
http://www.sophos.com/products/free-...i-rootkit.html
2. Try running Combofix (I've seen it fix oodles of stuff on mine and others pc's)
3. You might have gotten rid of the baddie but its infected your system restore which means you could keep getting re-infected unless you flush your restore points. (if you run combofix.. I think it does this for you) where did superantispyware say it was deleting the virus from?
4. If your familiar with Hijack this.. run it and see if you notice anything odd. If your not familiar with it.. they have a forum here dedicated to spyware, run it and let them give it a good look.
There is usually more then 1 program needed to completely fix all issues.. I am NO expert but have seen dozens of infected computers that need several steps till they were clean and clear.. Hope this helps!