Update: You may recall this thread was about failures of the factory navigation system, which also takes out audio and A/C controls as well. Mine died sporadically, the dealer replaced it under warranty and all has been well till now.
First, for some reason my new replacement audio system is a Sirius satellite radio instead of the originally supplied XM unit.
Anyway, I was listening to satellite radio and the sound died. The display was normal, just no sound. On any satellite station. Tried FM and Disc and audio worked, just not on Satellite. Got home and tried switching from Satellite to AM. Am came on but then could not switch back to Satellite. Tried FM, and it worked fine. Tried Disc and it worked but the sound was a combination of the disc and (I think) the satellite radio broadcast. Went around the controls for a while trying to get back to satellite until it locked up on AM and wouldn't let me leave.
All this time, the air conditioning worked fine, unlike the last time this thing failed.
Turned the car off, waited a minute and turned the ignition back on and everything worked per normal again except I had lost all my satellite and AM presets. The FM presets were still there. I can't explain it, but they were. The disc changer was back at the start of disc #1.
I guess it's back to the dealer. The vehicle is still under warranty and even if it wasn't, a whole new NAV/Audio/Air Conditioning box should last more than a month.
I'm just throwing this out there for public info. I'm deciding that Toyota or somebody really messed up in the design and execution of this piece of electronics. I just saw a post on a Tundra board where somebody's describiing the same thing in their truck.