I've got this really weird problem. Everytime I boot up my Mac Pro, right after the startup 'bong', I can hear barking and growling coming from inside it. If I open and close the optical drive to put in a DVD, I then hear a whimper and the noise stops for a while, but when I finish watching the disc and eject it I get bitten on the hand by something. Can anyone help?*
*I don't actually have a Mac Pro
(), just that seeing these threads — 'There's a hamster in my Mac Pro' and Dying Cat inside my MacPro... — at the same time were far too funny to let slide
. I'd link to that other thread about a scorpion in a Mac Pro, but the clicker on this MacBook I'm using is so knackered that I can't face anymore forum searching... 
*I don't actually have a Mac Pro