Cumulative Update 3 for SP1 for SQL Server 2012 caused a number of problems with SSIS packages. This also applies to database maintenance plans as they are also SSIS packages.
After applying the update, you could get this error when opening an SSIS package:
The type initializer for 'Microsoft.DataTransformationServices.Design.SharedIcons' threw an exception.
Value of 'null' is not valid for 'stream'. (System.Drawing)
If you edit a maintenance plan, you could get this error:
Provide value on 'System.Windows.Markup.StaticExtension' threw an exception. (PresentationFramework)
Exception has been thrown by the target of an invocation. (mscorlib)
The type initializer for 'Microsoft.SqlServer.Graph.Extended.HighContrastSupport' threw an exception. (Microsoft.SqlServer.IntegrationServices.Graph)
A fix has been released to address these issues. You should apply it in conjunction with CU3, whenever you are deploying CU3. You'll find details here: