Winforms – Visual Studio 2010 Designer Error on Run

I am using using VS2010 and if I have a form open in designer mode and run my application the designer tab will no longer show the form designer but instead an error will be displayed (and it is only fixed by restarting the IDE) saying:

"To prevent possible data loss before loading the designer, the
following errors must be resolved:"

1 Error:

"The designer could not be shown for this file because none of the
classes within it can be designed. The designer inspected the
following classes in the file: ##### — The base class ##### could
not be loaded. Ensure the assembly has been referenced and that all
projects have been built"

I then shows the following call stack:

at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.EnsureDocument(IDesignerSerializationManager manager)
at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager)
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
at System.ComponentModel.Design.Serialization.BasicDesignerLoader.BeginLoad(IDesignerLoaderHost host)

Any help is greatly appreciated this is really annoying.

Thanks,

Joel.