Make sure you are using the 'Sony BDP, HT, SMP' device profile in Mezzmo for your Sony BDP. Go to the Media Devices dialog in Mezzmo to check this.

If that still does not help, email us at support [at] conceiva [dot] com and we'll provide an updated device profile to try. In your email, please include the FFmpeg information on the DivX file that does not play. To do this, right-click on the video in Mezzmo and click 'Get FFmpeg Information'.