This must be a driver or configuration issue...
Fresh installation of Windows 7 x64 SP1. Have run all Windows Updates, Intel Updates, and Dell Updates. The keyboard works fine to get me into the CMOS and will get me to the Windows boot options screen (F8) for things such as Safe Mode. Keyboard does not work in Safe Mode or Normal Mode. BIOS version is the newest that Dell has posted (A01)
Reason that I say that is not a hardware issue. I booted to DOS using an old Windows 98 SE disk from an external DVD drive. At the DOS prompt, I have checked all the keys on the keyboard and all keys work under DOS.