Since it's not Windows XP failing, but a boot failure, causes range from failing drives to motherboards and other parts.
Call it in before you have to pay for repairs.
Save your data like you always do since hard disks tend to stop spinning without notice.
I have a HP Media Center PC and am running Microsoft XP Media Center edition. For a while now occasionally on start-up, my system will hang with a black screen and a flashing cursor on the top left corner. It does this right after I get the HP screen where I can go into BIOS or system recovery. So it begins start-up, I see the HP screen, I hear it try to access the floppy and then black screen with flashing cursor appears and nothing.
I wasn't too concerned about it as it always seemed to work properly on the second try. However, yesterday I had quite a scare. It took 7 or 8 tries before it started up again. Sometimes it would get past the flashing cursor screen, begin the windows xp start up screen, then go back to the very beginning with the HP screen and hang. Crazy! I could get it to start in safe mode a couple times, but not regular. Finally it workd. Any idea what might be causing this? I am afraid to shut down. I'll be doing some backups ASAP just in case this is serious.