I'd like to lock opportunities based on whether a custom field is set to true or false.  There has got to be a way - without having to create a new page layout... we want this to be active for all page layouts.  Any ideas?  I'm sure someone has done this.  Thanks!!

I'd like to lock opportunities based on whether a custom field is set to true or false.  There has got to be a way - without having to create a new page layout... we want this to be active for all page layouts.  Any ideas?  I'm sure someone has done this.  Thanks!!