When i try to create or edit existing dataflow task in ssis, i am getting following error:

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The Data Flow task could not be created. (Microsoft Visual Studio)
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Object reference not set to an instance of an object. (Microsoft.DataWarehouse)
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Program Location:
at Microsoft.DataWarehouse.Controls.DdsDiagramHostCon trol.Dispose(Boolean disposing)
at Microsoft.DataTransformationServices.Design.Pipeli neTaskView.Dispose(Boolean disposing)
at System.ComponentModel.Component.Dispose()
at Microsoft.DataTransformationServices.Design.DtrTas kDesigner.Dispose(Boolean disposing)
at System.ComponentModel.Design.ComponentDesigner.Dis pose()
at System.ComponentModel.Design.DesignerHost.RemoveFr omContainerPreProcess(IComponent component, IContainer container)
at System.ComponentModel.Design.DesignerHost.Remove(I Component component)
at Microsoft.DataTransformationServices.Design.DtsBas ePackageDesigner.CreateExecutable(String moniker, IDTSSequence container, String name)
at Microsoft.DataTransformationServices.Design.DtsPac kageView.noPipelineTasksWarning_LinkClicked(Object sender, LinkLabelLinkClickedEventArgs e)

Thanks in advance