I have the same problem with JBOSS Developer Studio.
Somehow it doesn't work anymore, since i replaced the seam 2.0.0 runtime with seam 2.0.1.
Unfortunately, the seam 2.0.0 download points to the seam 2.0.1 download, so i can not check this yet.
(I have a seam web project with EAR facet)
I have just created two new "seam dynamic web projects".
When i choose a seam 2.0.0 runtime, the above errormessage does not show.
When the seam 2.0.1 runtime is chosen, the error occurs.
please report a bug in jira with *exact* steps on how to reproduce it.
use jinq if you can and use Help > Report problem and attach the generated file.
Ah now I understand it.
please report this in jira as critical. we need to fix this one.
Link to this thread and the screencasts plus attach the output of Help > Report Problem after you have seen the "this page contains invalid values" error message.