Either your PC took a power hit and the power strip tripped off to protect it, or the kids were playing Donkey kong on CD and got the disk stuck in the drive (or put 2 in), or you have a saboteur...
Try using the manual eject on your CDROM drive (with the PC off, put an unbent paper clip in the small hole on the front of your CDROM drive to release the tray). If it comes out with a disk in it, remove the disk(s) and push it shut. Then try a restart.
Try tapping the delete key as you restart, if the previous idea didn't work. If your BIOS setup comes up normally, set the machine so your hard drive or floppy boots first, not your CDROM.
Worst case, unplug the CDROM power and signal (flat) cable and try. They could have fried the CDROM and it's hanging the boot.