Mysterious Rebooting of Computers

Hello,

Over the last few weeks I have started to see a strange thing happen with some of my computers in the office. When they put a CD into the CD Drive the computer reboots on them.

These computers range from PIII 400 Generic make and Dell PIII 700, 4100 Deminison series.

Could someone please suggest a couple of things I should look at or try in order that I fix this mysterious reboot. Any help would be greatly appreciated.