Terribly sorry to bump a old post, but I thought I would chime in just in case anyone stumbles upon this thread on Google like I did. The problem is caused by a gstreamer plugin for handling mpeg1 layer 3 being missing, I solved this eventually with the free mp3 codec from Fluendo, however then it complains about missing "audio/x-wav" which I have not yet found a fix for. I did however find a workaround, if you open the Digital Designer folder and rename the sounds folder to something else the program will work normally, the only downside is you wont have sound.
