I moved my iPhoto and iTunes files to a Lacie external hard drive to
free up space on my iMac internal hard drive.  Now when I export an
iPhoto slideshow with music to QuickTime, the music does not export.
How do I fix this?

im not much of an expert but you can try looking through the settings
of iPhoto of anything that should be changed after you moved the files
.. look for folder paths

try looking for an update for iPhoto to download, or in particular
something relating to the quicktime export

the last resort is to move the files back onto the computer hard
drive, then move them back after you finished exporting, but that's
what we're trying to avoid :P

check the paths in the iphoto settings.  Make sure they are associated
with the external drive, and not your local drive.  Do this for both
the pictures/audio folders locaed on your external.  Then, it should
work.

There is another potential problem.

If you are using a song that you purchased from iTunes, the music will
only play on computers that you have authorized computers only.  The
movie will work, but no music.

To get around this, you have to unlock the song with an utility like
hymm, re-add the song back to your itunes, then re-import it back to
your slideshow.

Cheers...

I have the answer, as I had the same circumstance. Do NOT export a
slideshow (doesn't work for me either).

Instead, select an album, then click on the > button at the bottom
("Display a slideshow of the selected items").

This opens up dialogue box with two tabs: (1) Settings; and (2) Music.
Select "Music" tab and select desired tune from your iTunes Library.
Then click on "Save Settings" button (bottom left).

Now, select desired images within your selected Album (Ctrl-A for
all). Select Share>Export from toolbar, then the QuickTime tab. Ensure
the "Add currently selected music to move" tick box is ticked on.
Click the "Export" button, and you should have a QuickTime movie with
music!

At least this has worked for me, with my iTunes songs all on an external hard drive.