I have had a problem with not being able to open PDO files with the Pepakura Designer 3. I think it has something to do with my computer because when I try opening the file, an error message pops up saying that the file format is not supported. Does anyone know how to fix this problem? I have searched for days for a solution, but have not been able to find one... This has frustrated me to no end. Can someone help me with this problem?