Airtunes Problems

I have an issue where Airtunes will not play a handful of songs in my iTunes playlist. It is a mix of songs that I ripped from CDs myself and songs that were downloaded. Every song plays correctly though the my MB speakers, but will not work through my Airport Express. The problem seems to affect every track in an album, but there is no discernible pattern as to what albums are afflicted. Any suggestions would be greatly appreciated...