If a mild tire vibration is enough to make the player cut out, I would seriously check the wiring and the internal cabling on the player. Especially make sure the disk drive cables are OK, the drive shock mounts haven't come undone, all of your wiring connections are soldered properly, and the wires are not pulling out of the crimps on the docking connector. The thing is designed to tolerate moderate vibration, and if it doesn't, there's something wrong with the installation or the player.