If your finder is only showing up the disc as 666 mb, its probably a support issue with discrecording.framework.
While this shouldnt happen with built-in drives, i had the same thing when i first bought my FW burner, Finder making discs only ~66mb (im having the same problem again since 10.2.8)
If it's the built-in drive from an imac, try searching the apple knowledge base, or contacting apple support.
i know the finder adds DesktopDB etc files to discs, but not 34 mb worth.