Problem and fix on my nuvi 350

Tonight, my nuvi 350 suddenly lost all detail in it's maps (North America version 8). It got stuck in a loop where it would say "calculating" on the screen (but no percent indicator of it's progress), the voice would say "recalculating" and then immediately "please drive to highlighted route", and then immediately "recalculating" again since there wasn't actually a highlighted route to follow. I tried resetting, and that didn't do anything at all.

I ended up going into maintenance mode (holding the lower left corner of the screen while powering on), and removed all user data (which only removes language, voice, and time zone, as well as restoring all other factory settings), and then the maps had all their detail back again. I have no idea what suddenly made the maps lose their detail, as I hadn't changed any of the user settings in several days, but I guess that is unimportant now. This may be useful to anyone else who has a similar problem. I was going to reformat and copy my backup over, but I am VERY glad I don't have to do that now.

Kelly