Are you generating Previews and have you opted to share them with iLife in the Aperture preferences? Can you access the Aperture Library from other apps? iMovie? A Word Processor? Mail?
If all you're trying to do is burn images to a disk you don't need iDVD or Toast, both of which are for making DVDs that play in domestic DVD players.
Just export the images to a folder on the desktop and burn that with the Finder.