I just un-boxed my new SC-05 today, and have been setting it up. MCACC seems pretty cool, and the PS3, XBOX360, Wii and HD-DVD player all work fine (PS3, XBOX and HD-DVD at 1080p, 1080p and 1080i respectively over HDMI, and the Wii through component). The only thing I'm having trouble with is the Mac Mini. The only resolution that seems to work is 1280x720, when all resolutions work when connected directly to the TV, including 1920x1080. I could deal with 720p, if only the video weren't offset by about 100 pixels to the left. The Apple menu and File menu are off the screen, and there is a black bar on the right side of the TV.
I've looked at the links on page on of this thread, and done many google searches, but can't find any references to a similar problem, let alone a fix for it. Everything says "Pioneer Elite receivers don't do any conversion to HDMI signals - what comes out is identical to what goes in," but I don't see how that's true if I'm having these two problems. The computer recognizes the "display" as "SC-05," so maybe it's not giving the computer the full range of resolutions supported by the TV.