Why subscription manager registration fails with '[ERROR] @rhsmcertd-worker:37' ?

Issue

• Subscription manager(RHSM) registration fails with -

  2013-12-04 12:10:10,793 [ERROR]  @rhsmcertd-worker:37 - Either the consumer is not registered or the certificates are corrupted. Certificate update using daemon failed.
  2013-12-04 12:10:10,889 [ERROR]  @rhsmcertd-worker:37 - Either the consumer is not registered or the certificates are corrupted. Certificate update using daemon failed.
  

• rhsm.log file has the following errors:

  2014-08-25 03:42:02,327 [INFO]  @rhsmd:185 - rhsmd: This system is registered to RHN Classic.
  2014-08-25 04:59:26,453 [ERROR]  @rhsmcertd-worker:41 - Either the consumer is not registered or the certificates are corrupted. Certificate update using daemon failed.
  2014-08-25 08:59:26,544 [ERROR]  @rhsmcertd-worker:41 - Either the consumer is not registered or the certificates are corrupted. Certificate update using daemon failed.