Okay this has me really stumped. I'm trying to listen to mp3s on my Captivate while it charges via the USB charging. When I try to use either Doubletwist I get the message "connected to computer and please eject the phone". When I try with the music player I get the message "SD card is being used as a mass storage device". I get these message if I have my phone hooked to a PC to charge, in my car or even plugged into a wall socket. Any idea why I can't charge it and listen to my mp3s at the same time?