i don't use playlists... i listen to "albums" but..
1. have you tried the ZUNE software for PC? It's really, really good and might work better.
2. on your Imagio i recommend S2P, even the free version kills wmp on winmo. unfortunately (fortunately?) it doesn't support the "library" so you must organize your files by artist folders.
http://s2p.ac-s2.com/
mentions several type of playlist support
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