Clip Zip weird behavior

A couple of weeks ago, my Sansa Clip Zip started to act strangely. Intersperse between the regular songs were accented a symbols, squares, and chinese symbols. If any of these items were selected the device would freeze. However, after formatting the device it would work fine again, until the strange files started to appear again. Now, my Clip Zip will function while plugged in to the computer (shows to be connected, can add and remove files, etc.) but when it is disconnected from the computer it will either immediately crash, hang on the Sansa logo, or hang on the “refreshing your media” screen after reaching a low point on the loading bar. Formatting the device has not fixed the problem now. Any help?