New minor patch from 2.0.3 to 2.0.4, available here.  (md5sum 696ec455445f4e21be490479a0739898)

To install, just place the downloaded file in your WoW directory and run BNupdate.exe.

There are no known patch notes for this.  I assume it was a critical update for Burning Crusades.

UPDATE:  Apparently the original file did not work.  Also,  it is only the 2.0.4 patch and not the 2.0.5 patch.  So I updated the link above with a working 2.0.4 patch file.  I'll see what I can find on 2.0.5 patch.