I was able to solve a similar problem by using a tip posted by "Kobai" on another forum http://forums.mycreativefansite.com/...zaic-ez300/15/
as reply #25 which is on page 2 of the replies to the post.
Basically, the user wrote a program to massage the .m3u playlist that Winamp or WMP11 puts out to make it work with Zen Mosaic EZ series players. The problem is that the EZ Mosaic uses DOS 8.3 short filenames in its .m3u playlists whereas Winamp or WMP11 (presumably, I use Winamp) puts out the .m3u playlist file using long filenames. The .m3u playlist files are just text files you can open with Notepad - so if you create one with the Mosaic EZ itself and then bring it into the PC and look at it with Notepad and compare to a playlist made by Winamp or WMP11 you'll see what is going on. The poster in the other forum, Kobai, just wrote a program that takes what Winamp or WMP11 puts out and converts the filenames. It is a bit klunky to use compared to something 100 programmers have refined over a few decades, but if you learn it it gets the job done in a flash.
I use iTunes to download podcasts and organize them so I can make up a playlist. I then import the iTunes playlist into Winamp to get it into .m3u format, then use Winamp to download it into a "Winamp Playlist" folder on the Mosaic. I then use Kobai's PlaylistMod.exe to take it from the "Winamp Playlist" folder on the Mosaic, convert it into something the Mosaic can use, and it ends up in the "Playlist" folder on the Mosaic which is where playlists the Mosaic can use are supposed to end up. Then the Mosaic recognizes the playlist and I can listen to it.