Videos start to convert then stop halfway-through.

Hi, I bought a Sansa Fuze and downloaded a SMC awhile ago and I’ve noticed a problem.

About half or so of the time when trying to convert a video, the program will start the conversion normally then stop at some point before completion. There’s no error message or anything, the % progress bar will simply stop progressing no matter how long I wait. This seems to happen at random times in the process (although always the same time on a individual video) and happens to various video formats all of which have other times worked. I was hoping someone here would know how to fix this, or at least what the problem is. I apologize if this is an issue that has been already addressed on these forums.