I was having this same problem... could load the caches via GGZ or GPX but after reboot they would disappear. If I connected to a computer and renamed the files, they would reload; but after the next power cycle would disappear. I tracked this down to the set of custom maps in my Custom Maps folder. There was either a bad file or bad filename or too many of them... not sure. Anyway, I renamed the Custom Maps folder to Custom MapsXX and it worked. I then deleted all of my custom maps except for one I really wanted to keep and all is well. I may go all them back one by one to see if it was just a corrupt file or if the naming was the cause or if just hitting a limit; but for not it works fine. Thought I would add this input to the thread in case anyone else stumbles upon this discussion and it helps someone.