domatlapuk, Thanks for the link. I had actually found that link before, but it included a Vista certificate, and I needed something compatible with Windows 7. However, following your reply, I flashed with the BIOS that you linked to and grabbed a 2.1 Dell certificate from another post. It worked! I wasn't sure if the certificate had to be specially matched to the SLIC table or whatever it is, but apparently it doesn't. Perhaps someone should clarify that point in one of the sticky posts. Thanks!
The certificate and the slic 2.1 should match, if your slic is dell you need certificate dell that goes like these DELL.XRM-MS