well, well, i should have tried this before i posted (anyway, maybe someone call tell me if this is a proper way to “delete” a capability):
from the file .project i deleted:
<buildCommand>
<name>com.genuitec.eclipse.hibernate.HibernateBuilder</name>
<arguments>
</arguments>
</buildCommand>
and:
<nature>com.genuitec.eclipse.hibernate.hibernatenature</nature>
after starting eclipse i were able to add the hibernate capability again…
kr,
guenther