You say that it's normal in some cars for the accessories to stay on after the key is off; but my player only stays on if it has locked up. Otherwise, it shuts down when the key is pulled.

No other symptoms that I can think of. Temperature doesn't seem to make a difference (it's never cool in KC in July, but it was below 80 this morning and I had the same problem as described; same thing yesterday afternoon when it was 90+). I'll check the cable and solder joint tonight when I get home.