Dont know about yours, but mine keeps rebooting when i put in an address or change maps.
I was recently in the US on a fly drive and purchased the Tom Tom Go 910 for this, but on the day of departure (isnt it always!) it decided to start playing up. Kept re-booting when I tried to put in the address of the Gatwick Car Park

Tried again in the US, sometimes it allowed me to change to US map, but most of the time it froze at this point or when I tried to put in the addressed I wanted, and then rebooted back to UK map.
Currently waiting on a reply to what to do, as I just want to send it back as its no longer needed and only purchased it for our US trips.