I'm pretty sure this is caused by using a set of headphones without a mic. The connection on most phones has a third contact for the mic, and when you use headphones without it strange things happen. My wife's erris was unusable with any normal headphones, but works great since we bought a pair with a mic at Radio Shack. My Droid is not as bad, and I use it quite a bit with her old ones, but it will still cause a pause or skip at times if it hit the connection.
Tim