I got mine working by reselecting the USA+Canada maps per one of their suggestions. I never would have guessed that would work but it did. This was their response to me:
We understand that you have attempted some self-troubleshooting. To ensure that all available steps have been taken, we ask that you visit our online assistance page at:
http://www.tomtom.com/6964
If these steps have all proven unsuccessful for you. There are several others we can try that may correct this. First, we will ask that you re-select your USA and Canada map on your device. Instructions to do so can be found on our website at:
http://www.tomtom.com/5345
After re-selecting the map, we will ask you to try and connect with our satellites. To do this, please take the device to an outdoor location with a clear view of the sky. It will be necessary for the device to be located outside of the vehicle when connecting with our satellites the first time. You can now power the device on, remain in one location and allow 5 minutes for the unit to receive the signal.
If this is not successful, we suggest performing a hard reset on your ONE 3rd Edition. Please note, performing a hard reset will remove any personal information saved on the system. It will not, however, remove the current application, map, or POIs on the device. Instructions for a hard reset can be found on our website at:
http://www.tomtom.com/7488
If you are unable to click the links provided above, please copy and paste it into the address bar of your Internet browser.
Once the hard reset has been performed, we will ask that you again take your device outside to receive an active signal (as outlined above). If your signal issues persist and your device was purchased more than one year ago, we will not be able to offer any further assistance. We do not perform paid repairs for devices that are out of warranty at this time. We regret any frustration that this may cause.