Hmm... it worked fine the first two times you ran it, then all of a sudden it freezes at the user screen?? I'm not sure if your able to do this, but at the user menu, try pressing the (-)zoom out key and the repeat button a the same time.
-If it does bring up the "secret" menu, try clearing user data.
-If you have a program that allows you to update the software, version 4.32 I'm guessing (or 5.14) then at that "secret" menu select NAND Flash Format and re-load the software.
If you can't access the "secret" menu and it locks up hard at the user menu w/out any responsiveness, I would suspect the hard drive is either bad or has corrupt data. I'm not sure if you can order just the hard drive from magellan/thales/tomtom/shaw but if you can then just replace the hard drive, nand flash format (above) and re-install your software via usb.
Additionally, not that it helps your problem, but atleast you would know the pwr and keypad work if this works, press Enter, Cancel and power button at the same time, as this SHOULD power off your unit.
Let me know if any new symptoms/problems come up or if you need further instructions.
on Jan 18, 2012