I had this happen on the 35i loaner I drove for 2 months. Ipod had worked flawlessly for the first month and then suddenly it wouldn't play. The Idrive recognized the ipod but wouldn't play anything from it (no sound). Radio, cd and everything else was fine. I ended up loading my music onto the hard drive and played it through there. I did take it to the dealer to see what the problem was and they said it was a software glitch that they have seen happen a couple of times (not just with the X3), but there was no known fix for it as of yet from BMW.
