Just upgraded to iPhoto '11 and when I click on an event and choose slideshow, it begins to play in reverse order (most recent first). My main Events homepage is set to sort descending by date and my photos are all ascending by date within the individual events. When I change the main Events view to ascending, it plays in the correct order, however I like my most recent events coming up first...I noticed I can get around this by opening the event and selecting the first photo and then starting slideshow. Is there something I am missing or is this just something I have to get used to?
In iPhoto 09 one could reverse the order of the slides very easily. However, that has been dropped in this version. You may have to create an album with the photos or use the original album the was used to create the slideshow and add the photos to a new slideshow in the order you need.
Had same issue but selecting first photo is also what worked for me. I always thought you had to select
all the photos in the event, album, etc... to include in the slideshow, but apparently that is not the case.
As an aside, I can't figure out what activates manual sort. It seems to come and go (greyed out or not) depending on whether I am in an event, album, smart album, etc...