By "crunching" do you mean your HD is constantly reading / writing? If so, I have seen this to be a couple of things:
1) Your hd needs to be formatted, either a "Zero All Data" or a low level format. Take the time to do one of the options as a straight init. basically only removes the directory structure (i think)
That has solved it for me on an older SCSI drive...
2) In a case where that didn't work, you could have a bad HD or some bad i/o component.
Maybe your problem is elsewhere, if you are losing power to your devices , i.e. your mouse?
Closed Captioning of this post is brought to you by your arse, in thanks for using cushiony soft tissue.