Deleted the map folder. Copied across the Europe_West 875.3613 map folder. Activated using Easytools. Rebooted TT, it fires up nicely, sats lock in and it moves as expected .. try to "navigate to" and it locks up then reboots.
Now downloading another copy of Europe_West just to see if it makes any difference. If it doesn't work I'll run with 870.3406 until WE 875.3613 becomes available.
Thanks for your thoughts