draftsight default program for dwg and dxf but will not open them directly

Running Draftsight on WIN7 x64.  I've installed latest update, but it didn't work on the last version either:- when I click a dxf or dwg file it will not open in Draftsight.  I have checked and Drafsight is the default program for these file types.

 

The error that comes up is:-

 

This action is only valid for products that are currently installed.

 

I can open the files only by dragging them into Draftsight, however this isn't easy either as you have to specify destination, scale, orientation etc.

 

Anyone any ideas?

 

Thanks,

A.