I thought this might be useful incase anyone experiences the same problem. I had an issue where xpages would not load at all. I would get HTTP 500 errors in the browser and a http jvm: severe: clfad####e: error on the console.
Turns out it is a cookie issue which actually stops xpages working! The error generated was:
java.lang.illegalArgumentException: Cookie name “some name” is a reserved token
My full blog post is here.
http://tech-shed.blogspot.com/2010/03/xpages-not-loading-jvm-errors-possible.html