| | I experience this all the time
I went through two usb cables thinking it was a cable problem. Now I have learned that the device needs to be connected when I boot up my PC. Also, if I disconnect the device for any length of time (I don't have an exact measurement, but I believe it is a half hour or so), it will go back into this mode. The only solution I have found is to reboot my computer.
It's a real pain when trying to charge or sync your device. Any further tips would be appreciated.