Problems with memory card on Garmin GPSes
I recently had a problem with a Garmin GPS (GPSMAP 60CSx) that crashed each time I updated the memory card with maps on my MAC. The root cause of the problem lies with the Mac writing some hidden folders into the memory card. It's some MAC metadata (._DS_Store, _.AppDouble, .Folders.)
The best solution I have found (except using a Windows based computer) is a small tool called BlueHarvest that removes these folders for you.