It sounds like your tags might be messed up. The Sandisk players like ID3V2.3 ISO8859-1 tags for the mp3 files. All other mp3 tags should be removed.
You can use the free program MP3Tag to easily correct the tags.
Are you using a memory card? If so, is it faster than class 4? The Sandisk players don’t like cards faster than class 4.
