I have a problem playing music on my iPhone 4. It's mounted on an arm attached to the car windscreen. When I drive along roads with less than smooth surfaces, songs frequently stop playing and skip to the next track. I drive 40 minutes each way to and from work and skips at least 4 or 5 times each journey. It's got to the point where I can predict where on the journey it will happen, depending on the road surface. Going over even small bumps and potholes will cause it to skip immediately. Sometimes there's a quick bleeping sound/tone as it skips. It reminds me of when I had a portable cd player in the car, with a 10 second buffer, but to be honest it's worse than that was. It doesn't skip if I'm listening to podcasts. I'm jailbroken on iOS 4.01. Anyone come across this or suggest a way to fix it? Edit - D'oh - the "shake to shuffle" setting seems to have been the problem. That and the crappy roads in Walsall.