registering XSD into the XML schema returns error ORA-01422: exact fetch returns more than requested

We are on rdbms 11.2.0.1 and have just begun to use XDB components and applications referencing .xsd and XMLTYPE.

First time we tried registering an XSD into an XML schema, we got this series of errors returned:

ORA-01422: exact fetch returns more than requested number of rows
ORA-06512: at "XDB.DBMS_XMLSCHEMA_INT", line 3
ORA-06512: at "XDB.DBMS_XMLSCHEMA", line 14
ORA-06512: at line 58When we run code that hits any XMLTYPE, it returns this error:ORA-19202:Error Occured in XML processingORA-00936: missing expressionORA-00942: table or view does not existORA-06512: at SYS.DBMS_XMLGEN, line 7ORA-06512: at SYS.DBMS_XMLGEN, line 147When we select count(*) from dba_network_acls, we are getting error:ORA-00600: internal arguments: [qmxqtmChkXQAtomMapSQL:2], [], [], [], [], [], [], [], [], [], [], [] Have seen metalink notes 1108619.1 and 1105245.1 and 429551.1, but the XDB component is VALID in the database.We also run the Oracle EBS 11.5.10.2 applications, so if there are missing privileges we just grant that will prevent the errors rather than reloading