jbroder - 6:41 pm on Sep 12, 2011 (gmt 0)
I didn't see anybody respond (it's a tough one), so I offer this in case it helps:
Have you tried isolating the header calls, with just a page that sets the header. Can you make the header do whatever you want? Make it a 500 when it should be 200, make it a 404 when the page is found?
Hope that helps...