How old is it? The battery could be wearing out. Did the battery show a full charge before disconnecting?
It never hurts to reload the firmware.
If you can get a computer connection, so you can see SANSA CLIP in Windows Explorer (Computer or My Computer), go to the firmware thread and reinstall the firmware with the Manual Update instructions. Basically, download the file, unzip it and drag the unzipped folder onto the SANSA CLIP driveletter.
http://forums.sandisk.com/t5/Sansa-Clip-Sansa-Clip/Sansa-Clip-Firmware-Update-01-02-18/td-p/280756
