I dunno if you've tried this yet or not, but if you use Windows XP, try turning off System Restore (Start - Programs - Accessories - System Tools - System Restore). Sometimes spyware and viruses will hide in your restoration files. Turn off restore, run everything again (and maybe check out SpyBot: Search & Destroy as well as Ad-Aware and your virus scanner). Then reboot and see what happens. You can turn System Restore back on later if you want.

This is what I had to do to get some spyware off my computer once. It took over and I was afraid I'd have to reinstall Windows too. If that still doesn't work though I've got a friend I could ask who helped me once before when I was in the same situation again...