open disk utility, do you have more than 1 partition? boot camp will only run if you have 1 partition.
or, it is finding something that it doesn't like even with 1 partition hence the error.
i've only seen it once myself, on a drive with 1 partition, so i had no choice by to clean reinstall OSX and go from there.
IIWY, i would reinstall OSX, then open boot camp assistant and try to install Win. once Win was installed, then i'd go back and copy my Mac files back.
Thanks to Bobthefisherman & Turbostar. Turns out I've got a corrupted disk (which I found out via "verify disk" on Disk Utility First Aid. Previously, I never thought to verify disk -- only to repair permissions -- so I never knew my HD had been corrupted.
Wasn't able to do a clean install of OSX10.6 because my SuperDrive only sporadically will load discs, so I am taking it to the Apple Store to see if they can do a clean install, and depending upon costs, get the Superdrive replaced.
The HD wasn't partioned by the way. And I did have just over 40GB of contiguous space.