Check the blog below:

http://blogs.msdn.com/sqlserverfaq/archive/2009/03/16/unable-to-create-maintenance-plans-after-service-pack-2-is-applied-on-sql-server-2005-fail-over-cluster-instance-running-on-windows-2008-cluster.aspx

Thank you very much for your reply...

I have tried executing the query you gave and received the following error message:

[Microsoft][ODBC SQL Server Driver][TCP/IP Sockets]ConnectionCheckForData (CheckforData()).

Server: Msg 11, Level 16, State...

I am able to execute all the queries, even the select queries with thousands of rows without any issues.....

However, I am unable to execute XP_CMDSHELL.....

I tried executing other extended stored...