There is a problem in the org.jboss.tools.birt.oda plugin introduced by fixing https://issues.jboss.org/browse/JBIDE-7052
Try to replace the org.jboss.tools.birt.oda plugin with http://anonsvn.jboss.org/repos/jbosstools/workspace/snjeza/jbide7052/org.jboss.tools.birt.oda_1.2.0.v20110809.jar
After replacing the plugin, you need to remove all files/directories except the config.ini file from the WEB-INF/platform/configuration directory.