I get the same problem - the program quits on me most of the time - occasionally it works, but mostly it doesn't! I can't work out what is different when it works to when it doesn't either - I've produced a 30 minute long slideshow without a problem, and now I'm having trouble getting it to work on a 5 minute one.
Very frustrating. It didn't work with aiff files, I converted them to mp3 but the program froze after a few hours and wouldn't quit. I ended up having to reboot using the power button on the front of the mac!
(G5, dual 2ghz, OSX 10.4.7, 4GB RAM, 500gbHDs, MotionPictureHD Version 2.1.2)
I'm using this program as it's the only one I get get to look good when viewed on an lcd tv - the otherwise far superior iphoto and idvd produced slideshows that look jaggy for a moment before sharpening, which is no good for my clients.