Mac Pro Screen Flash Clicking Sound


Hi. I'm extremely worried that some part of my hardware is dying.

Whilst in the middle of a logic 9 session the screen started to do the white flashing thing (like when u click outside a prompt box - but constantly). There is also a loud clicking sound from the mac and erratic mouse behaviour. The sound is not what I would usually associate with quieter drive related sounds.
(Please see short videos below)

The sound is constant but stops when say, I use iTunes but resumes as soon as I click to the desktop.

I've backed up everything. Also done a time machine backup. I can't boot up without pressing the shift key as it will boot straight into the apple hardware test mode (never seen that before). I've done a disk utility check from Osx CD and disk repair/verifying .. Nothing seems to help.

Does this sound familiar to anyone? Can anyone suggest any remedies?

I'm pretty much freakin out big time :(

Thanks :) ewan

Mac Pro 5.1 quad core intel 3.20ghz 8mb ram Osx


Well, I got some sound advice from a nice gal on Whirlpool....

I dug around fact i had found my old long forgotten klunky applekeyboard (shoved out of sight that i left plugged into the USB daisy chain to use its spare usb ports)... it had a cord wrapped around it.. finally yesterday tightening enough to trigger the non-stop key press of confusion.

causing the error flashing and clicking sound.