Ok, so I'm trying to put one of the macworld videos that I've downloaded on DVD. Not a problem, I've done it before. However, whenever I press burn and it finishes processising the menu's, the window pops up that says "You inserted a blank DVD. Choose an action blah blah blah..." and then iDVD closes unexpectantly. Well, I click "make this action the default" and click ignore, then try to burn it again, and the same thing happens. Why?