Problem amtetcher SNF 2009-05-28 18:00:52: "Turbo purge off" alarm

Ran recipe 3 (std. oxide) 3 times (chamber season + 2 etches). Each time, initial turbo pumpdown failed due to a "turbo purge off - program 3 ready" alarm. Silenced alarm and ran recipe again. Worked normally thereafter until running next etch after venting (bell jar only open ~3 min.), at which point the "turbo purge off" alarm occurred again.