Animations disappear after you modify a PowerPoint 2010, PowerPoint 2007, PowerPoint 2003, or PowerPoint 2002 presentation in PowerPoint 2000

When you edit a Microsoft PowerPoint 2010, Microsoft Office PowerPoint 2007, Microsoft Office PowerPoint 2003, or Microsoft PowerPoint 2002 presentation in Microsoft PowerPoint 2000, and then you reopen the presentation in PowerPoint 2010, PowerPoint 2007, PowerPoint 2003 or PowerPoint 2002, some custom animations may be missing.

This behavior can occur when you add an animation to the slide and then save the presentation by using the same name as the PowerPoint 2007, PowerPoint 2003 or PowerPoint 2002 presentation. Certain custom animations in PowerPoint 2007, PowerPoint 2003, or PowerPoint 2002 do not exist in PowerPoint 2000. Therefore, when you save the presentation in PowerPoint 2000, the PowerPoint 2007, PowerPoint 2003 or PowerPoint 2002 animations are deleted from the presentation. 

To work around this issue, when you open a PowerPoint 2010, PowerPoint 2007, PowerPoint 2003, or PowerPoint 2002 presentation in PowerPoint 2000 and then make changes to the presentation, save the presentation to a different file name.  

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.