I seem to be having the exact same problem with my new Dell XPS I just got. It has the SigmaTel C-Major Audio HD drivers installed (even re-installed the drivers from the CD and used Windows Update to get any later versions). I am running Windows Vista Home Premium. And I am running the latest version of
Tunebite.
I don't think it recognizes my sound card at all. When I go into the options for Audio it has three options in the drop down, (System Default, Digital Out (SPIF), Mic/Line in (or something like that). I think I am suppose to have Stereo or High Speed Dubbing in that drop down?
I have not tried your steps in post #8 yet but I might when I get home.