It seems like you have a log4j configuration file pointing to OnlyOnceErrorHandler. I suggest you look through your project (search in all files) for OnlyOnceErrorHandler and remove it.
Sorry, forgot to mention more precise: I tried to use the example
jboss-seam-jpaas explainded in
Getting Started, so no changes were made by me. This is the vanilla distribution.
I have seen in the logs there is an other error before all that:
A docBase /var/lib/tomcat6/webapps/jboss-seam-jpa inside the host appBase has been specified, and will be ignored.
So probably the whole context.xml as a source of the datasource will get valid in the container. Will look to resolve this.
The new version 2.1.0.CR1 did solve all the problems. Thanks to the team.