Slideshow speeding up

I’ve completed the slideshow tutorial (http://www.kirupa.com/developer/mx2004/xml_slideshow3.htm ) and I seem to have an issue with the rotation speeding up once I’ve clicked the next button. If I let it play without user intervention, it’s fine.

Any suggestions, aside from adding play/stop buttons? Any suggestions for stopping the slideshow rotation once a user clicks next or back?