Nuvi 50 Screen Lost Calibration

 

A Nuvi 50, about 6 months old just lost its screen calibration. Some buttons worked fine, others only worked if you pressed above their position on the screen, others couldn't be pressed at all.

Fortunately it was easy to fix by the screen calibration process (no thanks to Garmin for not including the steps needed in their documentation).

Has anyone else experienced this problem or know a cause?