Cannot open properties in Lectora Publisher

Today a problem started on my system - I can open a course file, but cannot open the properties of any pieces (page, question, etc.) I double click and right click but the properties window won't open. When I start Lectora, the initial window (new file, open, etc) doesn't diaplay either. I haven't made any changes to my PC, have plenty of memory, and disk space. Has anyone had this happen and what did you do?