Error partitioning new hard drive

I've searched high and low, on tom's hardware and elsewhere, but cannot seem to find the answer...

I just bought a new Western Digital SE16 320gb HDD, and I'm trying to format it. It's a secondary drive, so I'm formatting it through disk management. I get most of the way through the process (detects it, labels it "healthy", and even allows me to assign a letter to it), but when I try to format it, I get an error message saying "The operation did not complete because the partition or volume is not enabled. To enable the partition or volume, restart the computer."

...and that's what I've done... Over and over. I can't seem to find the answer to this question either, and I find it hard to believe I'm the only one...