Hello,
I am using JBoss portal 2.6.1. By default, jboss portal requires to have a page name declaration in the -object.xml
<page> <page name>default</page name> </page>
Just rename the word 'default' to 'Start' and that should work. This can also be changed using the admin console.
Using Admin, go to > Portals > default Portal >default Page and click on the Rename link and type what you want.