My unit regularly gets locked up into a state where it won't power on. The TomTom site has a procedure for getting around this that involves holding down the little reset button with a paper clip for 15 (30?) seconds and then turning it on. This works, but isn't possible to do when you try to turn it on as you're driving. This has happened to me a half dozen times since I got it. It seems like it might happen when the battery runs all the way down. Anyone else have this problem?