I just got my Virgin Mobile Intercept last weekend. Used it yesterday w/ the audible.com app and the aux port in my car, no problems. Plugged the phone into the wall last night (in a power strip) and had the stutter issue today.
Only thing I've done to the phone is inxane's recovery (Android ver: 2.1-update 1). Tried 4 microsd cards (2 8gb sdhc, the 2gb sd that came with it and another 2gb I had), mp3 & tunein radio have the same problem. Calls are fine though.
Tried uninstalling audible and deleting folder from sd card, rebooted phone twice. Yesterday evening I did notice that the Notifications bar wouldn't pull down, but after the first restart this morning everything but playback was fine. Second restart I left the phone off for 10 minutes.
The lady I was talking with at audible heard what it was doing and was on the line while I tried mp3 & tunein, her suggestion, which is what I'm probably going to have to do, was to return the phone and get it exchanged.
Just did the factory reset in inxane recovery, tried the mp3 from my sdcard, same issue.