How did you install the portal? The Quick Start Guide contains an installation section that uses the portal&appserver bundle. The Reference Guide contains a section on three installation variations - bundle, binary and source.
My guess would be that somehow CMS did not get installed, but I don't see how that is possible with either of the installation methods. By the way, I do hope that you upgraded to JBossAS 4.0.4.GA and Portal 2.4.0.GA.