Just wiping the card or formatting with Fat16 gives no guarantees as I experienced for weeks..
Apparantly there is a standard specificly for SD cards for formatting. Look in the wiki for a tool provided by panasonic to format the SD card properly so it will be recognized again by the V3. Don't think it was available for the MAC though.. But formatting once on a windows machine should make it work on a Mac later on anyway I think.
Good luck
