Ugh! Well I tried all of your advice.
The job that's stuck and cannot be deleted is an Inventory job. I could not tell it to Run Now because it was grayed-out. The only options I had were Delete, and Properties.
So then I ran the Repair utility and I thought that would work because then I could right-click the job and tell it to Run Now. It asked me for confirmation, then nothing happened.
So then I go to the Jobs screen and tried to delete it, it asked me for confirmation, then nothing happened.
I can't disable the drive it's assigned to because the drive is Unknown.
When I go to the job's properties, all I have is General and Notify. Schedule is not available like it is on a typical Inventory job.