I have an older tom tom unit.
Had a similar problem.
There is a reset button (you have to access it with a paper clip) on the back of my unit. Has happened a couple of times in the last 3 years. I or my wife use it daily. Always fixed the problem.
Also, I had a unit fall off the dash when the suction cup ripped from
constantly changing cars. Screen crcked.
It was within 1 year of purchse. Tom Tom sent me a new unit.
I took my functioning TomTom One unit on a business trip to DC. Picked up my rental car, plugged in the unit to find that it no longer worked. I bought the unit Summer of 2006 and have used it about 7-8 times since then. Worked great, but I was really upset in the rental car parking lot. Luckily, I also printed out a MapQuest route to my business meeting, otherwise I was going to be in bad shape.
Do you think I have any recourse for repair? Unit was getting power based on the lights on the unit and on the AC adapter. Just no activation.