Disable collision on the buttons you don't want to be clicked. Send the .capx file if you want, this should be easy to do.
Sometimes for this kind of thing I like to set up a global variable for MenuButtonEnabled, which has values of Yes or No. Where you have the 'on click' actions for each button, put these actions under when MenuButtonEnabled=Yes. During the 3 second timer when Play is clicked, set MenuButtonEnabled to No.