Today I was working on a Seam project and after modifying the pages.xml file and re-exploding to JBOSS the application server went into a loop and kept re-exploding over and over.
After some digging around I found out that it is a bug in JBOSS AS 5.1 and is being fixed in 5.2. Basically it is due to an Eclipse temp file being in either your WEB-INF/ or META-INF directory. The temp files to look for are either *.jsfdia or *.spdia and can be deleted. In my case the file was named pages.xml.spdia and was located in the WEB-INF/ directory along with my pages.xml file that was modified. After I deleted the file and re-exploded everything worked just fine.