Only other suggestions I have to try are:
logout and login again to see if its a role cookie problem
try a different skin to see if its a skin problem
try re-deploying the mojoPortal package in case some files are not up to date
check the logs for any errors
It won't really help me to see it if I cannot reproduce it I cannot fix it.
but also we cannot change the site - role permissions on the demo
I don't know what you mean by that, you can create test pages and test users and confiure the roles any way you want, just don't change the roles of the admin user.