This error is what I get every time I try to copy a track to my phone using the USB connection (can't use bluetooth). As long as I don't try to move any files the phone stays connected though. And it's also odd because I copied files this way before, I even use the same folder (the standard music folder). EDIT: SOLVED, this helped me: [Q] SGS 2 Drivers (CDC Serial & SAMSUNG_Android) - xda-developers and turning off all wireless signals etc. and making sure nothing is running, and a phone restart.