i also noticed this on my trip, it was only a 2.5hr drive, but i was thinking it was just my crappy junk gps receiver in my nextel phone, sliding all over the dash board while turning, and accelerating.

Or when i would skip songs with the remote control, it would cause gpsapp to freeze until the player stopped reading the song from the hard drive. Luckily I had a good down-down-down shuffle and not one of those not random enough shuffles

But every time gpsapp would freeze, it would resume within maybe 10 seconds at the most. I didn't have a complete lockup, but i also left gpsapp active on the screen, and only used the remote to change volume, and skip tracks (slowly, i would wait for gpsapp to update my speed, then skip to another track, then repeat)

Also, are you using just gpsapp? or gpsapp+roadmap?