KB934441 - Event ID: 26009 occurs after a MOM 2005 agent tries to fail over to the secondary MOM 2005 server
KB934441 has been released
https://support.microsoft.com/?kbid=934441
If you have multiple management servers with agents configured for failover and one of the managment server goes off-line agents may be refused a connection to the failover management server. A hotfix is available from Microsoft to correct this issue.