Maybe the one other player I tried (the RCA one) happened to be one of a few that won't handle the large playlist very well. Could be a coincidence, I guess.
I'm guessing you mean you have an HP mp3 player and not an HP iPod, as I don't think they ever made them. I think the iPod was strictly an Apple thing.
Maybe someone else will chime in soon and let me know about large playlists. Thanks again for your time.