@arkalos
Unfortunately that sounds suspiciously like physical flash damage, however you may be lucky and it's only a 'bad' re-formatting done previously. Garmin devices are quite sensitive to the way the internal memory is formatted so back up the entire visible file system and then format it using [Only registered and activated users can see links. ]. Copy the file system back and see how it then performs. If it won't accept a re-format it's toast.