Simon,

>OK, so I created a new form based on mmBusinessForm, added a tab control, some standard buttons etc., saved it, then went to try and create an inherited form from it....and got an error message saying: "The designer could not be shown for this file because none of the classes within it can be designed".

Sometimes this is because VS .NET can't find the parent class...are both forms part of the same namespace? If not, have you referenced the parent form's namespace in the child form's source code file? If you compile the project do you get errors? Fixing these errors should get rid of the designer problem you're experiencing.

Regards,