Flash 8 not working in PPT on others' computers

Help! I have successfully created several Flash 6 movies for clients’ PowerPoint presentations in the past. But now that I’ve been using Flash 8, they can’t seem to play the movie. They see the flat image in the slide, but they get this error message:

“Some controls on this presentation can’t be activated. They might not be registered on this computer.”

Active X control for Shockwave Flash is activated (they could use the Flash 6 movies no problem). Nothing has changed except for my use of Flash 8.

The only way it has worked is if they download the swf to their computer, create the PPT slide themselves, and play it from the same computer. Obviously, not a good solution since they will need to take the files elsewhere for presentations!