Did you render them as MPEG-II? Not all computers have the MPEG-II
codec installed. The machine you created the files on does because
you have Video Factory installed on it. If you don't need bitrates higher
than what MPEG-I provides, use that instead as any media player will be
able to play it. If you do need MPEG-II, then have your audiance use a
program like the CyberLink PowerDVD that comes free with most DVD
drives.
Choose advanced render, select MPEG as the Save As type, and then
click Custom. In the Custom Settings dialog, click the MPEG tab. You
can choose between MPEG-1 and MPEG-2 there, and if you wish you can
even save MPEG-1 as the default template.