Pathfinder RL80C Plus - No Chart Data

[RickC]

I bought a 1996 Sea Ray 370 Sundancer this summer. I used it several times with the above unit working flawlessly. I purchased a second C-Map chart for Georgian Bay as we were taking a 9 day trip out there4.
The unit worked fine again. On returning at the end of the trip I started getting "No Chart Data" on the bottom left of the screen and the screen showed a grey colour with no markings except Way Points. The range button when moved to any other distance than 3 NM and 6Nm showed the nothing screens. Any idea what the problem could be and if so a solution.
The boat is out of the water for the winter so thought I might get som input to work on the problem over the winter.
Thanks