I'll note it here, may be it will be helpful for anyone receiving a similar request.
Had a rather weird request to convert a powerpoint presentation into a .scr screensaver executable. I tried with the many tools available on the net for that (mostly shareware, but paying was not an issue in this case), but had little success. Either they crashed, or they opened powerpoint without doing anything or didn't even start.
Changing approach proved to be helpful (although you lose the transitions and the animations):
Export the powerpoint presentation to multiple images
Convert the images to a flash animation using (http://www.flash-slideshow-maker.com/)
Convert the flash file to a .scr using Instantstorm (http://www.instantstorm.com/forum/viewtopic.php?id=529)
In the end I chose another way of doing it: convert the pps to pdf (either with Microsoft PDF addon or via PDFCreater and then use the swftools and pdf2swf)