Did this start right after the updates?
Previously, the following helped. While connected to your PC, navigate to your North_America_2GB map folder and look for a file called mapsettings.cfg. This contains your recent destinations, favorites, etc. Copy that file to your PC's desktop and delete it from the unit. See if that stops the rebooting issue.
If that solves it, you're only out your favorites and recent destinations, and if you have a backup of your unit (something you really should have in any case), we can probably even recover those for you.