For most problems with DVD Imager, in all likelihood the content of the VIDEO_TS folder (or other content if you're using copy mode) is something DVD Imager can't handle.

Here are some ways to try to determine that.

Start by using a utility like Onyx to

1) Repair permissions.
2) Check preferences.
3) Clean caches.

Are there any DVDs/VIDEO_TS folders that DVD Imager can copy? If you've ever successfully used DVD Imager to make a DVD before, try inserting one you created with DVD Imager before or one that was created a different way, and try to perform the operation on the VIDEO_TS folder that exists there.

Monitor the tmp folder while DVD Imager is working. That may present a challenge. You should be able to locate that folder in the Finder by typing command-shift-g and entering "/tmp". Examine the files in the lelandtmploc just after DVD Imager begins working.

Look for a file called " dvdimagerlog" also in the "/tmp" folder. If you can, drag it out of there before DVD Imager deletes it when quitting, and tell me what's in it. If you have trouble dragging it, just select it as soon as it appears after you click Create in DVD Imager and press command-d to duplicate it. That way the original will be removed when DVD Imager quits but the duplicate will remain.

You might want to try testing the mkisofs executable which is the engine for DVD Imager. The documentation includes the command you need to type into the terminal, substituting your particulars for source, disk name, and destination.

If you put the DVD Imager application into the main directory of the boot drive, typing the following line precisely into Terminal and pressing return should result in a message telling you all the options that can be used for the mkisofs executable. If it doesn't, then there's some problem with the mkisofs executable on your system, and DVD Imager can't possibly work.

/DVD\ Imager.app/Contents/Resources/mkisofs

If you get the expected response, then try completing the command line using the command line sample included in the documentation.

Good luck!