Hold down you reset button for thirty seconds. The unit will then reboot.
If this does not fix your problem, you can go to the Tom Tom site find your unit and downlaod the latest updates. You will need to link your unit to your a USB cord a USB port on your computer.
Unable to get valid GPS signal on my Tom Tom Always says unable to get valid GPS signal This lasted...
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Unable to get valid GPS signal on my Tom Tom Always says unable to get valid GPS signal This lasted for a 2 hour journey yesterday