Kind of a related question.
I now and again have a gpx file which won't work, usually because I have done some tinkering and mucked up its " grammar" (sorry can't remember the computer term - syntax?). Though not uber techy i usually manage to find the problem, maybe a space or improperly closed "bracket". Are there any progs, possibly named above, which you can just run a gpx file through to find and highlight issues?