Aha.
My LCD display is all bolloxed up, since I got the car. It shows nothing half the time and Egyptian heiroglyphics the other half. So I didn't see that it was giving me a message.
I am taking the car for warranty service for the display, and was wondering if they needed to look at the wiring too.
Good to know that it will only run for an hour like that also.
Between the display not working, and the delay between pushing the button and actually getting sound out of it, there have been a couple of times I could have sworn the radio was turning itself back on after I killed the engine, and I was worried it would just start itself up in the middle of the night and drain the battery.
Thanks for the info, I will sleep better.