I had the same problem when I bought my 7D, and was REALLY upset about it because I didn't know if I would be able to return it. I did some reading and found that running the manual sensor clean option for a minute or two most times fixes the "dead" pixels. The regular sensor clean didn't fix the issue for me, but when I did the manual sensor clean and let it sit for a couple minutes, then turned it off and back on, my hot pixels were nice and black. Maybe give it a shot on yours.