Um, I think I know what the problem is. Had this happen to me today, for the second time. Powered up today, after battery change a couple days ago. It said I had no geocaches. Was driving my mom around, not actually caching. So, waited until I got home, hooked it up to the computer and went to look at the drive the SD card is assigned (I keep downloaded cache files on an SD Card on the 64) and said there was no disk in the drive. Light bulb went on in my head, so I pulled the back off, took out the batteries and sure enough, the locking mechanism on the SD card was loose again.
You know the batteries can be a little challenging to change in this unit, as they're in there pretty tight. I was in a hurry when I changed them the other day and I think it knocks the locking mechanism loose for the SD Card. So, I re-seated the card, made sure it was in the lock position, put the batteries back in, and voila...there were all the caches.
Now, if you are losing the file info and you keep your files in the area the original preloaded cache file was (the one with the useless 250,000 geocaches), and you don't have/use an SD card, I don't know what the problem might be. I opted to delete that original cache file and created a folder on the SD Card called Garmin and another folder UNDER that called GPX and I have about 15 .gpx files in that folder. These files are pocket query results downloaded directly from gc.com. Not created through importing into Base camp, not created using GSAK. Just 15 separate files, with about 1000 caches each. Unlike the DeLorme I had, I don't have to load each file. The 64 sees all the caches in all the files at once. Pretty nice and so much less work.
