ISAPI Filter Won't Protect One Site

[Klingenstein, Nate]

The actual content that was being protected was apparently causing IIS to choke hard enough that the Shibboleth ISAPI filter never got a chance to run.

It's not clear why similar content worked in staging, it's not how Apache works, and it's not how we expected IIS to work.  But fixing the underlying content worked.

Thanks to everyone for the suggestions.  Hope this relic helps someone.