Ric,
I Think I can help if this is winforms.

Item # 1 :
When you subclassed the form, in the construtor, did you leave the InitializeComponet(); line?

Item # 2 :
Go to the main form
Go to the code window
Look for the line of code that opens the UserWindow
change this code to call your window

mmAppDesktop.FormMgr.Show(new mmUsersFormLang(), this);
change this line to
mmAppDesktop.FormMgr.Show(new YourUserFormName(), this);