It's a Compaq Armada M300 running XP Professional. After the Compaq screen, it goes to an error message that says Windows did not start successfully - this might be caused by a recent hardware or software change (I can't think of any). It then gives me options to start in safe mode, safe mode with networking, safe mode with command prompt, start Windows normally, or use last known settings that worked. No Matter which option I choose, it goes to the XP loading screen for a few seconds goes back to the Compaq screen and it starts again. I don't have the XP installation disc for the computer. Any idea what's going on? Thanks.