A persistent virus, please give me some advice?

I have Norton AntiVirus 2003 (with latest updates installed) and Webroot Spy Sweeper. These things have worked fine up until this point..

Norton detected two Trojan horse viruses which were successfully removed. These past few days, a warning from Norton popped up saying that it discovered an 'VBS.Redlof.A" virus, but it was unable to repair it. When I click okay, nothing happens. When I run a system scan-- it says there is nothing there. Is this possible? It can tell me it's found a virus, send me a warning message...and then say there are no viruses present in the system scan? I've tried to remove it manually, but I can't find it in the files.

If anyone can explain this-- please help me! My computer is running really slowly lately, and I'd love for a solution to get rid of the VBS virus! Thank you so much in advance.

Also, I run scans for spyware, it's found and eliminiated...and then upon reboot it's back again. 'Apropos' is always found when I run a scan. And no matter how many times I delete the spyware- it comes back again. I'm assuming this has something to do with the virus? My hope is that when I manage to delete the virus the random re-spawning spyware problem will go away too.

Thanks for any input you can give me, especially in ways to find the virus and get rid of it.