FND_DCP.REQUEST_SESSION_LOCK error on starting Concurrent Managers

Following error reported in Concurrent Manager logfile on starting CM :

Starting ERP_1228@ERP Internal Concurrent Manager -- shell process ID 5996

          logfile=/logs/ERP/conc/log/ERP_1228.mgr
          PRINTER=noprint
           mailto=appldev
          restart=N
             diag=N
            sleep=30
             pmon=4
           quesiz=1
          Reviver is ENABLED

Routine &ROUTINE has attempted to start the internal concurrent manager.  The ICM is already running.  Contact you system administrator for further assistance.afpdlrq received an unsuccessful result from PL/SQL procedure or function FND_DCP.Request_Session_Lock.
Routine FND_DCP.REQUEST_SESSION_LOCK received a result code of 1 from the call to DBMS_LOCK.Request.
Possible DBMS_LOCK.Request resultCall to establish_icm failed
The Internal Concurrent Manager has encountered an error.

This must be due to a blocking session in the database.

Either bounce the database and re-start CM or follow :

1. Run sql to check for blocking session :

SQL> SELECT v$access.sid, v$session.serial#

FROM v$session,v$access

WHERE v$access.sid = v$session.sid and v$access.object = 'FND_CP_FNDSM'

GROUP BY v$access.sid, v$session.serial#;  2    3    4

       SID    SERIAL#

---------- ----------

       523         17

SQL>

2. Kill blocking session :

SQL> alter system kill session '523,17';

System altered.

SQL>

Start CM.