Model space objects not visible in  viewport but they print out OK

Hello,

I need help with this one - 2 desktop PC's with a brand new installation of Draftsight are showing the same fault - the viewport does not show any objects drawn in the model space.

If the cursor is moved around within the viewport then the greyed out image of the objects appears along with the grab handles. What is even stranger is that when I do a print preview all the objects are visible. Its not a layers setting, graphics card or line colour problem - all these things have been tried & ruled out.

This problem appears to be identical to these community posted questions:

Objects do not appear in viewport. & No graphics appear in viewport

What makes it even worse is that there is a 3rd fresh Draftsight install and that machine shows no problems - everything works OK. All machines are running Windows7

Is this a known bug with Draftsight and what can I do to make the program work as it is intended?