New device. Works fine from battery power only, it arrived with 50% battery life so I used it for a while without connecting the car power cord and everything was normal. When I connected the power cord I got a symbol on the screen of the device connected to a computer, and it rebooted. I re-entered the destination and as soon as I did it re-booted again. Rinse and repeat. Could not be used for navigation until I unplugged the power cord. How weird is that? An ideas for a solution?
Just to be clear you're talking about the Garmin cigarette lighter power adapter that came with the 1350 right? If so either that or the 1350 is faulty as SUSSAMB said.
Many 3rd party power adapters cause a device to enter mass storage mode although I haven't heard of any causing reboots.