PQs lately not showing up in my Nuvi 500...

[+e-bird67]

My "back-up" GPSr is a Garmin Nuvi 500. I prefer my Garmin Oregon 450t for hiking caching, but seem to have recently misplaced it. Anyway, in the past year or so, I have experienced intermittent problems with my Nuvi. When I copy over a PQ into the GPX folder, there's a 50/50 chance that I will be able to pull up any of the caches on my unit when I try to select a cache from the menu. Sometimes, if I delete and copy over again, it will work, and sometimes it won't. I never had this problem the first year or so with this unit. The way I load the file is simply to copy the .gpx file and paste it into the appropriate GPX folder. I cannot seem to figure out any kind of pattern- it truly seems to be random. When I look at the folders on the computer with the unit connected, the file is there, but when I unplug it and turn it on, the caches don't show up. Has anyone ever experienced this problem before? I am stumped!