The Nuvi is up to date and using latest Garmin POI loader.
In the past I have successfully installed the GPX files but now there seems to be a problem.
Something weird happening there, as I use the GPX files on my 765t and never have a problem fortuneatly. Are you using the SOX.EXE program also? Only a wild guess..
I can't get the GPX files to work either, I always get a message that there is a format error on line 2 of the code and POI loader can't/won't continue reading the file.