When posting an issue, please include enough details for others to understand what you're seeing.
In your case, you should include at the very least:
version of seam
what you did to cause the problem (startup or hitting a certain page)
Having said that, I just tested the dvd demo (from cvs on Jboss 4.2.0 - 1.2.1 is known to work on 4.0.5) myself and it's working fine. I suspect you have an issue in your environment.