Recently my Garmin suddenly goes into autoreboot while I was driving, and it was unable to load the map even if it was powered down and restart.
The problem was believed to be caused by too many Favourites and custom routes created on the device. After performing a master reset the device was able to boot normally, except that all the Favourites created were wiped out, so make sure you backup all your custom data on the device every now and then.
1. Start with the unit OFF and unplugged from power
2. Touch and hold the lower right corner of the screen with an index finger or the eraser end of a pencil
3. Continue touching and holding the lower right hand corner of the screen then power the unit ON
4. Release the power button when the device powers ON
o You will see a new message: Do you really want to erase all user data?
5. Remove your finger from the touchscreen when this message displays
6. Touch Yes*
The device will automatically reset. Follow the on screen prompts and then place your device in an area with a clear view of the sky until it acquires satellites.
Had my 765t refuse to take an extra route, (done in Mapsource) until I deleted others. Only had 3 small routes on the GPS so it appears that the onboard memory may be too small to store more than a couple.
Avoid creating too many Favourites or Waypoints
