This afternoon when I got home from work, the battery in the '05 was completely dead, so whatever was running this morning had exhausted it.
I put the charger on. I removed Fuse 6 from the trunk-mounted fuse block and the running sound, which was coming from behind the fuse block, stopped. I also removed Fuse 26 in the block at the driver's side of the dash. I charged the battery for several hours, then reinstalled both fuses, and Ta Da! The radio works perfectly. The car started right up, and everything seems back to normal. I let it idle a couple minutes then shut it down and the running sound stayed about 20 to 30 seconds, then stopped. I left both fuses in, and left the charger on overnight to get a good charge. This seems to have been a sort of reboot which hopefully got everything going normally. I will be out of town a couple of days, and look it over when I return.
By the way, this Car is pretty-much the standard car: no navigation system, no super seats, etc. and there was no vacuum pump underneath the back seat. Whatever was running all night and all day was like a hard drive maybe but I am not certain what it is except it seems to have something to do with the radio.