Java Database Connectivity (JDBC)

Hi all, I use JDBC with java 6. Environment is:

OracleOracle Database 11g Release 11.1.0.6.0 - 64bit Production
Oracle JDBC driver 11.1.0.7.0-Production

I created a simple table with a constraint, then I inserted one row:

CREATE TABLE Test (
name VARCHAR2(40 char),
UNIQUE (name)
);
INSERT into Test VALUES ('any');

Fine so far. Then - after connecting through JDBC - I repeated the above insert 16 times using conn.createStatement().execute().
I got all the times an expected error (ORA-00001) because of uniqueness violation,
but after inserting one more row I got:

ORA-17002 IO exception: Software caused connection abort: recv failed

At this point connection was closed. Similar effects can be achieved though other constraint violations.
Stack trace is:

java.sql.SQLRecoverableException: IO exception: Software caused connection abort: recv failed
at oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:101)
at oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:133)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:199)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:263)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:521)
at oracle.jdbc.driver.T4CStatement.executeForRows(T4CStatement.java:958)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1222)
at oracle.jdbc.driver.OracleStatement.executeInternal(OracleStatement.java:1770)
at oracle.jdbc.driver.OracleStatement.execute(OracleStatement.java:1739)
at oracle.jdbc.driver.OracleStatementWrapper.execute(OracleStatementWrapper.java:299)

I couldn't find any solution after googling around.
Thanks for any suggestion.