Your LoginForm can use delegate to LoginMethod in MDIContainer Form. Until user not correct enter name and pwd, Menus will be not enabled. If you want, i create project 4 you. Sry 4 my English. Tom

You can use this fragment: YourForm frm; foreach( Form mdi in this.MdiChildren) { frm = mdi as YourForm; if( frm == null ) continue;//this is other form //frm.YourProperty; //frm.YourPublicFunction(); return; }