Hi Valentin,
I am a coder, and i work currently with PHP on a medium project. I use Dia to create some model, like actor diagrams, database diagrams... I create some documents with Dia 0.95 under Windows and now i can't load them with Dia 0.96 (Win).
I think you should file a bug report in http://bugzilla.gnome.org and attach a sample of a problematic file so that the dia developers can follow up. Regards, Steffen