I was installing and configuring a phpBB forum today and very often I got to see "Access to the Administration Control Panel is not allowed as you do not have administrative permissions.". I was wondering as to why I get into this error often. When I surfed the Internet, I was able to see that many who got this error ended up in a reinstall of the entire forum!!! Are you getting into the error "Access to the Administration Control Panel is not allowed as you do not have administrative permissions."
But as far as my knowledge goes, this is just an error when your session expires. Just relogin and things should start working!