This is an issue with the menu you have selected (many potential reasons as to what could have caused the error. Please follow the below instructions which i use to resolve this issue:

Create a new project with a new name (Place something in the project in-order to save the project) leave it open. Go to file>openproject, and select the project that you have been unable to burn (Be sure to select add project). Copy all of the contents out of the old project into the new project ( once the content has been copied go to the menu and select window, at the bottom of the menu options should be the name of both projects, select the new project and paste the content from the old project into the new project. Go back to the old project by selecting windows and the appropiate proect. Go to >file> manage movies> and select remove from project. This will delete the old project from the new project. Proceede to burn new project using a diferent menu. This will resolve your issue