Why does JBoss Negotiation not work with Seam applications?

Issue

I have jboss negotiation toolkit working. I also have it working in an application which uses Spring Security. However, when I try to incorporate it into our Seam application it fails.

I am using the version of Seam and JBoss Negotiation that ships with JBoss 5.1.2. I am running Java 1.6-45, on a Windows 7 box. I have used the instructions that are contained in the Seam posting at http://seamframework.org/128602.lace

My observations:
1) The SPNEGO processing starts.
2) SPNEGO says it is sending the 401
3) it shows the header
4) The next thing in the log indicates that it has suddenly gone to the default "other" login method and tries to do a file based login.