For the first time my GPS was informing me of an invalid file. I had to systematically remove files and restart the GPS for the past few hours until I narrowed it down to one in the Port Norris area. In the process I noticed how slow the files would install back in the GPS and it brought to mind the fact my GPS is really slow refreshing the map files as well. I am going to have to purchase a new card to see if the refreshing will improve.