Zapping PRAM and Open Firmware

When troubleshooting abnormal Mac behavior, one of the most prudent courses of action is "zapping" the PRAM (Parameter Memory). This is done by holding the [Command]+[Option]+P+R keys (or for those on a standard PC keyboard, [Windows-Key]+[Alt]+P+R), during startup.

If anomolous behavior persists after zapping the PRAM, another more serious option is "open firmware". On startup, hold down the [Command]+[Option]+O+F keys (or [Windows-Key]+[Alt]+O+F for those on non-Mac keyboards). This brings up the open firmware screen. At the prompt type reset-nvram and press [Return] (or [Enter]). At the next prompt, type reset-all and press [Return] (or [Enter]). The machine will then reboot.

Should the abberant behavior still persist, there may be a more serious problem with your Mac, bad RAM for instance. In this case, you must troubleshoot the hardware components and attempt to alleviate those problems separately.