It turns out that this may be related to the problem I described in
this thread... In my case, the hard drive IS running when the unit does not boot up (stays at the Pioneer logo screen), and will sequentially play songs from the library; however, only the volume buttons work, so you can't navigate tracks when it gets into that mode, and even then, the unit will randomly decide to stop playing one song and go to the next, sometimes skipping entire songs along the way. I can also switch sources in this situation, and the radio and iPod interface work, just with no display.
It IS due to heat, but I don't think it gets up to
122 degrees in my car. Besides, my iPod lives in my glove box, and it has been there for at least a year and a half, and has never had any problems with its hard drive in that time.
Last Saturday, I took my unit back to Sound Advice (where I bought it--about a 140-mile round trip for me), and since it was an overcast morning, the unit worked fine all the way down there, and they could not reproduce the problem when I got there. They did reset the unit and unplug and reconnect all of the wires to the unit; I gave them the benefit of the doubt, thinking that
maybe one of those two things may have helped, but of course, Sunday it exhibited this same problem again. So I'm taking it back one more time, and will insist on a new unit or a full refund for this system (they offered to remove it and send it to Pioneer for service, which could take "up to six weeks," but I doubt that Pioneer would go through the trouble necessary to reproduce this problem in their repair facility). The bottom line is, if it's sold in Florida, it should
work in Florida, and if that's not the case, it should be Pioneer's loss, not mine.
I'm hoping that this problem only occurs in a relatively small number of Z1s, and that replacing the unit will take care of it; if all of them were susceptible to this heat-related problem, it seems like there would be many more people seeing this than have reported it so far.