plugging in USB cable shuts down sansa 4gb player

I’ve had it plugged in for 24 hours now and there is no difference at all in either the battery charge (80%) or its response when plugged in or unplugged.  My wife has an identical player and I plugged it in to all USB ports on my computer using both usb cables and it connects and charges normally.  Mine just goes black still.  Must be a usb internal problem.  Any other ideas before I trash it?