It sounds like the processor is being over taxed ... maybe even by a corrupt waypoint ...
It would be a good idea to get all your Nav data into HBPC and look for irrelevant coordinates, irrelevant waypoint dates, duplicate Waypoints, and anything suspicious of corrupt Nav data ...
It would also be a good idea to test the unit recording without a map card as this can take some resources also ...
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On another note ... Low and/or insufficient power can create weird functionality in the unit features ...
Rickie