Slideshow rotated photos

Try to quit iPhoto after rotating the photos, before you start the slideshow, see this support article:

http://support.apple.com/kb/TS3659

What is your iPhoto version? The latest updates fixed bugs related to rotation.

Try this: launch iPhoto with the Option key held down and create a new, test library. Import some of the same photos and test to see if the problem persists. Does it?

Are there a lot of those photos? If not export them to a folder on the Desktop (Kind=Original) and losslessly rotate them with the free app Xee Xee. Import into iPhoto and use in the slideshow.

OT

OK, now itr's time to repair your main library. Apply the two fixes below in order as needed:

Fix #1

Launch iPhoto with the Command+Option keys held down and rebuild the library.

Since only one option can be run at a time start with Option #3, followed by #4 and then #1 as needed.

Fix #2

Using iPhoto Library Manager to Rebuild Your iPhoto Library

1 - download iPhoto Library Manager and launch.

2 - click on the Add Library button, navigate to your Home/Pictures folder and select your iPhoto Library folder.

3 - Now that the library is listed in the left hand pane of iPLM, click on your library and go to the File ➙ Rebuild Library menu option.

4 - In the next window name the new library and select the location you want it to be placed.

5 - Click on the Create button.

Note: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments. However, books, calendars, cards and slideshows will be lost. The original library will be left untouched for further attempts at fixing the problem or in case the rebuilt library is not satisfactory.

I just had this same rotation and the Genius Bar helped me with the fix which went like this:

-copy each photo to the desktop

-open the photo in Preview

-rotate to the proper setting

-save and move back to iPhoto