Nuxeo crashes after database transaction error

We observed at multiple time that nuxeo dm stops to serve requests after the occurence of a PostgreSQL error.
At the same time, Arjuna starts to warn about transactions that are not recoverable.
The temporary workaround that we have found is to manually remove the postgreSQL prepared transaction and to restart the server with a cleaned tx-object-store.

Following is an extract of exceptions reported in server log :

Caused by: org.nuxeo.ecm.core.api.WrappedException: Exception: org.postgresql.util.PSQLException. message: ERROR: insert or update on table "hierarchy" violates foreign key constraint "hierarchy_parentid_hierarchy_fk"
Detail: Key (parentid)=(30243e0f-f1f8-4113-93b8-14d3de03850a) is not present in table "hierarchy".
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1608)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1343)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:194)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:451)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:350)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:343)
at sun.reflect.GeneratedMethodAccessor142.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.postgresql.ds.jdbc23.AbstractJdbc23PooledConnection$StatementHandler.invoke(AbstractJdbc23PooledConnection.java:477)
at $Proxy374.execute(Unknown Source)
at org.nuxeo.ecm.core.storage.sql.Mapper.insertSingleRow(Mapper.java:799)
... 48 more

2009-09-14 13:42:21,763 WARN [com.arjuna.ats.jta.logging.loggerI18N] [com.arjuna.ats.internal.jta.resources.arjunacore.norecoveryxa] [com.arjuna.ats.internal.jta.resources.arjunacore.norecoveryxa] Could not find new XAResource to use f
or recovering non-serializable XAResource