title: ORA-12528: TNS Listener: all appropriate instances are blocking new connections. Instance "CLRExtProc", status UNKNOWN
body: <p>I'm getting this error if i try to login as db user. If <code>lsnrctl</code> status is run i get the below error.<br> DB was working fine all these years and stopped working suddenly.</p>
  
  <pre><code>Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=ABC.LOCAL)(PORT=1521)
  STATUS of the LISTENER
  ------------------------
  Alias                     LISTENER
  Version                   TNSLSNR for 64-bit Windows: Version 11.2.0.1.0 - Production
  Start Date                19-MAY-2014 12:18:17
  Uptime                    0 days 0 hr. 22 min. 51 sec
  Trace Level               off
  Security                  ON: Local OS Authentication
  SNMP                      OFF
  Listener Parameter File   D:\Oracle\Administrator\product\11.2.0\dbhome_1\network\admin\listener.ora
  Listener Log File         d:\oracle\administrator\diag\tnslsnr\abc\listener\alert\log.xml
  Listening Endpoints Summary...
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=ABC.LOCAL)(PORT=1521)))
    (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1521ipc)))
  Services Summary...
  Service "CLRExtProc" has 1 instance(s).
    Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
  Service "devdb" has 1 instance(s).
    Instance "devdb", status BLOCKED, has 1 handler(s) for this service...
  Service "testdb" has 1 instance(s).
    Instance "testdb", status BLOCKED, has 1 handler(s) for this service...
  The command completed successfully
  </code></pre>