"- Execute maintenance plan. Backup Weekly (Error)
Execution failed. See the maintenance plan and SQL Server Agent job history logs for details."
There was no log file in the maintenance plan log so I checked SQL Server Agent job history and found the message stating the server access issue.
Please post that error (from the agent history).
07/31/2012 14:06:30,Backup Weekly.Subplan_1,Error,0,SERVER1,Backup Weekly.Subplan_1,(Job outcome),,The job failed. Unable to determine if the owner (XX\mrtrich99) of job Backup Weekly.Subplan_1 has server access (reason: Could not obtain information about Windows NT group/user 'XX\mrtrich99'<c/> error code 0x5. [SQLSTATE 42000] (Error 15404)).,00:00:00,0,0,,,,0