Which sound system do you have? Base , Hi Fi or L7/hk
You must have idrive since you said hard drive.
The Aux and USB inputs come throuth the combox or
TCU/Mulf. Its possible those could be going bad.
If you have streaming bluetooth music it will mean you have
a combox since it is the only module that supports this.
http://www.e90post.com/forums/attach...2&d=1260829447
These modules are located in the same area as the TCU in the above
document.
If you have a TCU mulf combo the mulf is under the TCU.