Unable to burn playlist to cd

I am using windows 7 latest itunes version Sept 1 2015 and cannot burn playlists of my own music to a cd. That is, music which has not been purchased from the itunes store, but which is in my library. I have just checked the drive is burning OK by successfully burning a cd using windows media player, and...oddly enough I can successfully burn a podcast to cd. But for everything else, nothing hapens and then a message says it is cancelling the burn. Never used to have a problem. Just started happening today. Last successful CD burn was in late July.