|Not much in the way of details....|
Have you made any BIOS setting adjustments? (Clear CMOS jumper and load optimum defaults)
How old is the computer? (CMOS back up battery may need replacing)
What computer (if stock name brand)? What main components (if not)?
Any other problems or errors?
Any hardware changes recently?
Any details may help us help you.
You have to be a little bit crazy to keep you from going insane.
If all else fails, read instructions.