CorelDraw X7 hangs after failed tiff export

I have a simple cdr file with an invisible but printable layer.

Attempting to export this file to tiff I get a warning "Invisible objects will be printed". If I press "Cancel" on the export screen at this point I can no longer export the file (e.g. after changing the attributes of the hidden layer)--the "export" option on the file menu is grayed out.

What's worse, I can't thereafter exit the program. Attempting to close Corel produces an error warning that " . . . Some tasks that were performed in the background have failed. Check the status bar of each open document ..." Status bar says nothing, the document window won't close. The only way I found to exit after this point is by ending it in task manager.

Tried to simulate the same problem with exporting to other file types but that works OK

I'm using X7 education edition with Windows 10

Has anyone else encountered this problem? Is there a solution?

     Ilan Sharon