>I want to have a VFP program starting from Start menu and freeze the windows until the correct password (barcode) is entered.
>Is there anything that can help me to do that?

Win95 is already running, the user launches a VFP application, and the first form presented to the user is asking for a password? If you make this a modal form, the user will either have to enter a valid password or quit (cancel) the app.