You could try downloading the latest firmware and installing it manually on the player. The firmware in the player may be corrupted. The issue of the pause button not working can also result from pressing the pause/play button before the player fully boots up.
http://forums.sandisk.com/t5/Sansa-Clip-Sansa-Clip/Sansa-Clip-Firmware-Update-01-02-18/td-p/280756
