I am having the same issue as you with one of my three Mac's running 10.5.6. I tried your fix, but with no luck. Took just three pictures, chose add, chose slideshow, and I never get to a menu to adjust the settings for the slideshow before I get the spinning colorwheel and then the program crashes. My other two Mac's do not have this issue. This one is a PowerPC Dual 1.8 G5 tower with 2GB Ram. Any ideas?
I fixed it. Fix is below:
Mac Fixit had a post where someone who had dual monitors was having the same problem. They were able to resolve the issue by switching the monitors to "mirror" mode and starting the slide show. After it ran successfully while the monitors were mirrored they were able to switch back to "split screen" and play slide shows.
Following their example I was able to resolve the crashing issue and now the slide shows work perfectly.