When I'm in iDVD and go to burn a disc it goes through all the steps and at the last step where it asks if you continue and burn it freezes and won't allow you to push the okay/yes button and ejects the disc. This happens with several slideshows and also several DVD's. We are using DVD-R's. Does anyone know what could be causing? We're doing this on a MacBook that's approximately 3 years old and it's running Leopard.