I use Windows XP Professional on P4 2.0 GHz, 256 MB RAM machine. The OS automatically updates itself as it is always online. I generally hibernate my system at the end of the day. But yeaterday when I tried to shut it down, it simply didn't !!!!! It even doesn't restart!!! It only Hibernates!!!! After a hard reboot also, the problem persists! What's wrong? Some virus or something else?