It is a strange issue with the designer. Everything still compiles and runs but you can no longer use the designer to edit the form. Here is a stack trace form the designer window:
at Microsoft.VSDesigner.Data.VS.SqlCommandDesigner.Initialize(IComponent component)
at System.ComponentModel.Design.DesignerHost.AddToContainerPostProcess(IComponent component, String name, IContainer containerToAddTo)
at System.ComponentModel.Design.DesignerHost.PerformAdd(IComponent component, String name)
at System.ComponentModel.Design.DesignerHost.System.ComponentModel.Design.IDesignerHost.CreateComponent(Type componentType, String name)
at System.ComponentModel.Design.Serialization.DesignerSerializationManager.CreateInstance(Type type, ICollection arguments, String name, Boolean addToContainer)
at System.ComponentModel.Design.Serialization.DesignerSerializationManager.System.ComponentModel.Design.Serialization.IDesignerSerializationManager.CreateInstance(Type type, ICollection arguments, String name, Boolean addToContainer)
at System.ComponentModel.Design.Serialization.ComponentCodeDomSerializer.DeserializeInstance(IDesignerSerializationManager manager, Type type, Object[] parameters, String name, Boolean addToContainer)
at System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeExpression(IDesignerSerializationManager manager, String name, CodeExpression expression)
at System.ComponentModel.Design.Serialization.CodeDomSerializer.DeserializeStatementToInstance(IDesignerSerializationManager manager, CodeStatement statement)
at System.ComponentModel.Design.Serialization.CodeDomSerializer.Deserialize(IDesignerSerializationManager manager, Object codeObject)
at System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.DeserializeName(IDesignerSerializationManager manager, String name, CodeStatementCollection statements)