Here's a riddle for you. I have the song Float On by Modest Mouse(it's a good little tune), well I have two copies, shows how much I pay attention. Anyhow it's an interesting case study I think. One copy was ripped from a CD, and one copy I bought from itunes. The itunes one won't make a Genius playlist, but the ripped one will. I changed their tags so they match EXACTLY. Itunes still won't use the one I purchased from them, to create a Genius playlist. Now what on earth could possibly be the reason for this? It's obviously not the tags. The ripped one is 3:29, and the itunes version is 3:28. Other than that they are identical in file name, tags, etc. The only difference one being an mp3 and one being an m4p. Just thought it was odd. Thoughts?