I need to replace all standard textboxes on forms in a project to a textbox class I have created.

I wrote a program that went through each form in the project, used it as a table and replaced the class & classloc fields with the correct class and class library name.

All went fine and the app runs properly.

Whenever I open and then close a form in design that has the textbox class on it however, I am unable to then open the textbox class - a dialog box states = "Unable to modify a class that is in use".

It is as if the class is opened when the form is opened but is left open after the form is closed.

Any ideas as to what is going on ?

Cheers,
Jamie