OK, guys, call me whatever you want, but the disk works now. I post the solution for others who wouldn't think about it.

After I finalized the disk and tested it, I printed out a CD/DVD label and put it on the disk (yes, on the correct side). However, that label prevented the disk from being used in my player.

Just for giggles, I pulled the label off, and presto... the disk works in my player. My coworkers and I are theorizing that I didn't put the label on exactly square, and the weight of the label was throwing the balance of the disc off enough to prevent a correct read. Oh well.