I am having a similar problem to the one described in the following thread:
Only I am experiencing the problem on a 4GB Sansa Clip.
The audio file is a DRM WMA from NetLibrary, 165MB, 32kbps, and 11:48:01 in length.
I am currently at the 5:21 mark in the file, and the stuttering is getting to the point where it’s difficult to listen to the file.
I had filled the device (mostly music, some podcasts) then deleted files, filled it again, etc., so there may be some fragmentation that is accounting for the problem.
I am reformatting the clip using the device’s internal format function and will copy only the audiobook onto the device initially to see if the problem goes away (this *should* minimize if not eliminate fragmentation). Then I will resync the rest of the music files onto the player using Windows Media Player, and then see if the problem comes back.
I will post my results here.