Adaware recently detected a virus on my netbook (EEEPc with XP), but I have been having problems with Windows not shutting down, so the virus could apparently not be properly deleted without a normal shut-down. Lately, when on the internet, a new window opens automatically, because of the virus, so I immediately shut down iexplorer. Tonight, I was searching for how to make my netbook properly shut down, when I got called away from my computer. Unfortunately, the virus must have opened the window it had been trying to open before, but since I wasn’t there to stop it, it was successful in doing whatever screwing with my computer it had been trying to do. When I came back, the computer had shut down and attempted to re-boot, but now will not completely re-boot; it comes back to the choice of boot options (safe mode, most recent successful, etc.), but none of the them work. So now I need to try to boot from a portable CD drive. I suspect your problem is a similar virus.