I have had a computer for a year with XP Home installed and all of a sudden I started it up a few days ago and it came to the desktop but with no icons or taskbar. Windows asked if I wanted to activate the product as if it never had been activated I choose yes and then it just logs off. I choose no and it just logs off. It will not let me go to the last good configuration or safemode in any form. What gives has something been corruppted ?