DinØ,
There are times that C3D appears to not be working, and Windows will conspire to tell you that it isn't; most cases it IS working and the task will finish. You will note there are a few long pauses in the recent XDREFS tutorial, as I meditated, and read the Help file waiting for it to return a COMMAND line prompt.
Old habit from LDD desktop, ENTER through the promts, until COMMAND line appears. Otherwise it would leave most of your SYSVARS in dissarray. This isn't the issue here, however I have noticed that STRAY clicks, or any form of input while it (C3D) seems to not be working, will surely make it stop.