Old Toad, I see that you really know your iPhoto/iDVD products. I have a similar problem, perhaps you can help.
I have an iMac 24" that I purchased in 2009. With it came iLife '09. I've been creating slideshows and movies with iPhoto/iMovie/iDVD and been very happy with the professional-looking results.
Tomorrow is my parents' 50th anniversary. I decided to make an elaborate slideshow of their lives, with some photos going back to the 1920s. So, a couple of weeks ago, before starting the project, I decided to upgrade my iPhoto '09 to '11 so I can get any benefits from the improved software and any additional slideshow themes. Bad decision, as I found out late last night while trying to send the slideshow to iDVD for finalizing the project (I know, I should have done this earlier).
As you can imagine, my beautiful slideshow which renders great in iPhoto '11 (I'm using the Scrapbook theme) is not doing too well in iDVD (version 7.1.2). Photos are stretched, images that are part of the theme are missing, etc. When I saw this happening, I checked the discussion forum and came across the incompatibilities between iPhoto '11 and iDVD. :-(
So now I'm at a crossroads. I managed to borrow an MBP from work which has iLife '09 installed. Option A would be to export the slideshow (and photo files) from iPhoto '11 to the MBP and attempt to recreate the slideshow there, send it to iDVD on the MBP and then burn the DVD. Option B would be to somehow downgrade iPhoto '11 from my iMac back to iPhoto '09 (not sure if it's even possible) and hopefully the slideshow would render in iPhoto '09. Option C would be to pack up and take my iMac with me to the place where we're having the event tomorrow and connect it directly to the HDTV which is being used for the show. From the iMac I can present the slideshow, but it will not have the nice, clean, UI of a DVD.
Needless to say, I have a lot of work to do tonight, no matter which way I go. I just hope not to screw something up, so I'm grateful for any advice you (or anyone else) may have.
Thank you in advance.