I've created a DVD with a motion menu and 6 clickable items on the menu. One of them is a Photo Slideshow of the event that is depicted in the main video.

The problem with the photo slideshow is that each photo flickers when it comes on the screen, a white flash comes over each shot as it dissolves onto the screen.

The entire DVD has been created on a Mac using Final Cut Express 4 for the 5 videos and iPhoto for the 1 slideshow. The final DVD is burned in iDVD.

Searching the Internet for help shows that this flicker problem goes all the way back to 2004! I haven't found a single result in the web search to show that Apple has fixed this flicker problem up to now. What workaround can be used to fix this problem? Is there another Mac program that would do better? The only solution I can come up with is to place all 153 photos on a timeline in Final Cut Express 4, manually insert 152 transitions, then export it as usual and place into iDVD as a movie instead of a slideshow. I hope that's not the only option available.

I have never use iphoto on my slideshow so I can't help you with that, I use this:
Boinx Software - FotoMagico - For Video Editors (http://www.boinx.com/fotomagico/finalcut/) without any problem. I have no affiliation with this company.
I have use their product and its great.

Thanks for the reply. Will keep the link. I've placed all the photos on a timeline each cross-dissolved and exported as a .mov movie. The final presentation is far better than iDVD making the photo slideshow.

I use iphoto 08, export with my own settings as a QT movie, then you can take it into iDVD to make a DVD. You can use Ken Burns effect in iphoto by clicking on "This Slide" tab and adjust start and stop positions, add music, but only one song apparently-it's buggy, but you can make each slide as long as you want. There are also some cool transitions choices to choose from. Hope this helps!