go to the bios and see if you have a listing that will return the bios to the default settings, if not then unplug the power from the wall, press the power button for approx 5 sec., then open up case and pull the cmos battery for 5 minutes, then plug back in, also make sure there are no peripherals attached, only monitor, keyboard and mouse.
this will set back to default settings and you will have to go into the bios to set the time and date to the correct numbers and reset any settings that you may have set before.
look under the drive listings to see if it recognizes the harddrive, and the cdrom.
then reboot and did that clear up the loop or at least give you a blue screen with a file or program that is causing the issue.