Audio Video sync problems

Sansa Fuze 2GB

Firmware ver: v01.01.11A

Media Converter ver: 1.0B004.236CDG

Original video … audio insync

Converted video… audio insync

Video playback on Fuze … audio lags

I have confirmed that the audio and video match everywhere except for during playback on the fuze device itself. For playback of the converted *.avi file on my computer there is a slight (barely perceptable) difference in video and audio. This I am sure is do to the actual conversion on the orginal file, and it not a big enough of a difference to cause problems. However when playing the EXACT same *.avi file on the fuze I get a good 2 to 3 second difference of the audio lagging behind the video.  

Any ideas? Software caused? or maybe hardware performance issues? Insufficent amount of working memory on the device?