I have been having this problem on my sansa clip.
This may not be the easiest way but it should work, but you’ll need itunes or a tag editor.
First I copied the mp3 files from my clip to my harddrive. I then opened itunes and drag and dropped the files into a playlist
(Make sure you go to Edit \ Preferences \ Advanced and have "Copy Files to Itunes Library Unselected first)
I then highlighted all files, right clicked and chose “Convert ID3 Tags”
This part is iffy, and can be done several ways, what i normally do is check the first box and leave it at none. Then redo it and switch to 2.3.
At This point make sure all have the correct track number, and this should fix it. Copy the files back to the sansa.
IF that didnt work, rename all track file names in itunes by right clicking and naming my track number starting with 01, 02. 03…
and then recopy back to sansa over old files.
