I have been doing battle with the same issue for around 6 weeks. At this point, the only way to get a selected few songs to play is to use the Musicmatch Jukebox and Supertag each and every song. Next, sit back, cross your fingers and if you're very lucky a few of the songs that you've supertaged will actually load AND play. I can get songs on the player (on occasion) but they won't play - there doesn't seem to be a pattern for which songs will work and which won't.
Another option is to go to the support website, download the MTP Recovery Tool and reformat the player. I've done this but had only limited success getting songs to transfer and play.
Sorry I can't give you an absolute fix - there doesn't appear to be one. Good luck, and if you find something that works all of the time, please let me know.
just got an iriver H10 and napster to go. Downloaded a bunch of songs to player and none of them will play on it. They are all there but none will play any help would be greatly appreicaited cause neither iriver or napster have got back to me. Thanx

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