Maybe this is a little farfetched, but if one of the singers (especially someone like Michael Jackson) asks for a percentage of the profits, that could be a deal breaker as well. But hopefully this date will stick and we won't have to wait until 2004 until Season 4. :)
I have a feeling that it has less to do with music issues than it has to do with syndication. After all, they obviously have contracts to replay these episodes over and over on TV with the music, so hammering out a DVD contract shouldn't be too hard. My guess is that the more seasons that FOX...