I then had the following from Tom Tom Support, which again didn't work, but might be of use to someone.
It details backing up, formatting and reinstalling.
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I would request you to format your TomTom device and check if it resolves the issue.
If you haven't already done so, please download and install the latest version of TomTom HOME from [Only registered and activated users can see links. Click Here To Register...].
STEP 1 - Creating a backup of your map
- Charge your unit for at least two hours (preferably via the home charger)
- Perform a reset on your device (see: [Only registered and activated users can see links. Click Here To Register...] )
- Connect your device to the computer and turn it on
- Open the Home software, go to page 2 and press on the "Manage My Device" (Go, ONE, XL) button.
- Tick Map, Postcode and Speed Cameras and then press on the "Copy to Computer" button
IMPORTANT: We advise you to follow the next steps ONLY if you have made a successful backup of your map.
STEP 2 Format your device
- Open My Computer; you will see the TomTom device as a removable disk drive.
- Right click on the TomTom device drive and choose 'Format' (Please make sure quick format is not selected)
On a Mac:-
- On a Mac, you can format the disk via 'Disk Utility', Select the TomTom drive and select 'MS DOS File System' and press erase.
The application can be found under Applications > Utilities > Disk Utility
After the Format has completed, please disconnect your TomTom device from your computer.
It will now have a red cross on the screen.
STEP 3 Open TomTom HOME
- Log in to your account with your email address and password for your TomTom account.
- On Page 2 of TomTom HOME, click on ‘Manage My TomTom -> Items on Computer’
- Tick the option for ‘Applications’
- Tick the option for ‘Voices’
- Click on ‘Remove Selected Items’
STEP 4 Install the Application
- Reset your TomTom device as shown on [Only registered and activated users can see links. Click Here To Register...]
- Connect it to your computer and THEN turn it on
- HOME will now search for updates automatically. If not please click on “Update my Device”
- A list of updates should appear
- If there is a TomTom application (with the green puzzle piece icon), please ensure it is ticked
- Click on 'Update and Install'
- Once complete click on Done and your device should reboot itself
- Once it connects again it will look for more updates
- When you have a new list of updates please click on Back
- Disconnect the device by clicking on the Blue Eject button in the bottom right
- Now connect again and repeat STEP 4 to install any further Application updates until no more updates are offered
STEP 5 Restore the map back on device
- Connect device to HOME
- Click on Add Traffic, Safety Cameras, Voices, etc in HOME
- Click on 'Items on my computer' on last page
- Click on 'Maps' and select the map
- Click on ADD
Safely disconnect device from HOME.
This should resolve the issue.
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It then goes on to say how to get the system info and to send TT Support that for escalation of the problem. of which there it is :-)