...Hey guys I know this is a bit off topic for a post being that I am talking about a car stereo setup. I just recently invested in a new car stereo receiver. This is my first time having a nice stereo that has bluetooth phone, bluetooth pandora, HD FM/AM, iPhone/iPod, USB, and Auxiliary capabilities..as well as being sirius xm ready...I understand that the phone has to be paired with the stereo to use the bluetooth phone feature as well as the pandora feature. What I am interested in doing is figuring out how the USB audio is supposed to work..I have the the phone plugged into the stereo..The phone is set to the (Media Device) setting...The stereo is set to the (USB Audio) setting...but yet my stereo is still reading "FILE NOT FOUND" I am confused whether this would be a setting problem on the Phone or the Stereo...My goal is to be able to play my MP3s stored within the SD card memory of my Droid RAZR ICS 4.04. My stereo is an Alpine CDE-HD137BT. If anyone has any knowledge on this I'd definitely appreciate the help. Thanks guys.