Without trying to recreate those specific codes, let me GUESS what is happening, at least this is what happens to me.
Sometimes music that was available in the marketplace (and was downloaded) is no longer available. Occasionally, the same album or something very similar is released, perhaps with the MP3 option available for format purchase. Try this: move a track from
the album by dragging it outside the Zune folder system, such as on your Desktop. Then open the Zune software.Highlight the album in your collection, then right click and choose More Information option in the marketplace. Does it show as "Not available"? That's
a clear sign that the album is no longer available. Look for the same album elsewhere in the marketplace. If available, download it and delete the non-working version and its files.
The other situation you describe might be harder to pin down. Does it always happen when you try to download a new song? Have you tried other albums, other songs? Have you restarted the Zune software? Have you logged off and logged back into the Zune software
user account?
Again, check to see all the keys describe on 7/20 post are installed.