[zipper]

A little more detail from the Int'l Herald Tribune article:

http://www.iht.com/articles/2005/09/06/news/crash.php

"Investigators pieced together the story of the crash from numerous sources. In the wreckage, they found the first solid clues - the pressurization valve and an air outflow valve set incorrectly. Air traffic control tapes provided information on the confusion in the cockpit."

[snip]

"The plane that crashed, a Boeing 737, underwent maintenance the night before. The maintenance crew apparently left a pressurization controller rotary knob out of place, according to the officials connected to the investigation, and the crew did not catch the mistake during preflight checks the next day. This meant that the plane could not pressurize."

[Bob]

"The plane that crashed, a Boeing 737, underwent maintenance the night before. The maintenance crew apparently left a pressurization controller rotary knob out of place, according to the officials connected to the investigation, and the crew did not catch the mistake during preflight checks the next day. This meant that the plane could not pressurize."

<speculation>

IIRC, when Payne Stewart's plane had its cabin pressure failure, they talked about a 'bleed air valve' (or some similar term) being the cause. This may have been the control for that valve.

</speculation>