ORACLE - Binary MisMatch

Issue - Oracle 11gR2 alert log has following error:

WARNING: Oracle executable binary mismatch detected.
 Binary of new process does not match binary which started instance
issue alter system set "_disable_image_check" = true to disable these messages
Thu Jul 18 15:47:12 2013
WARNING: Oracle executable binary mismatch detected.
 Binary of new process does not match binary which started instance
issue alter system set "_disable_image_check" = true to disable these messages
Thu Jul 18 15:47:17 2013

Solution:
alter system set "_disable_image_check" = true scope=both; and Restart the database (optional)
(Ref Doc ID: 369260.1)