Obvious question: You've left it for a decent amount of time (say, 20 minutes) with a good view of the sky? Is it failing to see any signal at all, or just never getting a lock? A hard reset (or severe crash) will clear the ephemeris data, so it may take a while for it to receive it all before it can begin to calculate a position.
There's something seriously fishy going on if a dodgy GPX file can break the GPS receiver, seems more likely to be coincidence.