Geocaching and downloading caches on a GPSMap62

I have no problem getting caches to download on the GPSr, but if I unplug it from the computer then plug it back in, all the caches that I have downloaded disappear. They're still in the unit, but I cannot bring them up on the screen. And if I download another cache, it's the only one I can find. How do I go about finding the ones I had already entered??

 

Say if I make a list of caches to be found, send them to the GPS through the "send to my GPS" on geocaching .com and all is well. I can see all of them. but if I want to add another cache later, the only one that shows up is the added one. I can plug the GPS to the computer, and they're all there, but they don't show up on the gps.

 

I have the same problem on the GPSmap 66st. I found a way to work around it by creating a GPX folder on my computer to hold all gpx files I have downloaded. Then when it happens I can restore them by connecting the gps to my computer and deleting ALL .gpx files from the Garmin gpx folder and then reboot the garmin. Then I hook it back up to the computer and then drag and drop them back into the garmin's (now empty) gpx folder from the backup folder I created on my computer. When I power the garmin back up they are all there again.