Oven that cuts out?

Can anyone advice me on the problem I have got. It is a Indest oven that cuts out after about twenty to twenty five minutes. When I say cuts out I mean turns off with all electrical connection. No light or illuminated dials. Once it cools down then it will work again. Then turns of again after twenty minutes or so. I would be very gratefully if someone knows what is causing the problem. Many thanks.