AE spawns a blank dialog box and then Hangs

After working for usually 15-20 minutes on a project in the Beta, it suddenly hangs for no apparent reason, even if I am not actually doing anything at that point in time, and that's it, the only way out  is via Task Manager and the big red switch, loosing any work you may not have saved in the interim period.

There is no apparent pattern as to what I may have been doing immediately before, but just maybe it has to do with resizing a control, typically a Shape, which does seem to fit  my occurences quite well ?.

W10 Pro, 16Gb Ram, I7 processor, GTX 980 GPU.