Why does my eMachine keeps restarting?

Mac mini keeps restarting?

• Hi My mac mini keeps restarting, restarting, and never gets to the desktop. Its actually my cousin's computer. I borrowed it a month ago, but got a chance today to actually look at it. The computer was sitting on the floor for 3 weeks, and no one even touched it. But today when i tried to restart it, it keeps rebooting and rebooting. This is my first time using this computer. It was working fine at my cousin's house but its not working at my house. I even tried booting from the mac os cd, but i get the same thing. Is it overheating or something. I really have no idea. Can I have some help from you guys. Again, its restarting over and over again and never gets to the desktop. Is it the hard drive or something.. Thanks in advance.

• Answer:

  Unplug everything but one display, the keyboard, the mouse, and the power cord. Reset the PRAM (a.k.a. NVRAM). Reset Open Firmware. Restart holding the alt/option key for 30 seconds. If it boots to the "Startup Manager" screen, wait to see if it reboots on its own. If not, the hardware is fine. If so, it needs service. Even if you are in Death Valley, it won't overheat in one minute of use unless it is defective. If the hardware is fine, restart holding the shift key for 30 seconds. If that fixes it, you probably have some sleazy software loading in the Login Items of your account.