Post SQL Server 2005 SP2 Fix
Microsoft recently released an critical updated for post SQL Server SP2 Fix related to issues noticed after applying SP2 with existing SQL Server 2005 maintenance plans and Integration Services packages that contain cleanup tasks run those tasks at shorter intervals.
Refer to :
Microsoft SQL Server 2005 Service Pack 2 issue: Cleanup tasks run at different intervals than intended
https://support.microsoft.com/kb/933508
Critical Update for SQL Server 2005 Service Pack 2 (KB:933508)