It might be other than actual dvd format.
It might be a cd image (not sure if that is even relevant).
You might not have 100% of the image. how you obtained the files might matter. The drive you are attempting to read it from might not be up to the task. The drive you are attempting to burn it with might also not be up to it.
If Imageburn is stymied though you sure have a problem.
Have you altered the file name in any fashion? I have sometimes gotten too clever for my own good renaming a file, only to have to undo the name change because I had mangled something in the process. And your result happened.