Fixed it - after two days trying to solve this. I just by chance tripped over the answer.

If this helps anyone, this is what I found out.

When I tried to save scene, or even a render - seemed Maya crashed. Turns out it did not.
I noticed the cursor would move to the bottom left of my main display.

So I started Maya again, went to save scene as...
Maya freezes? Again?

I used Win7 command (win key, shift, arrow right.)

This forced my main window/scene/app - etc. to display on my 2nd monitor -
Also using Win trick the save box appeared on the 2nd monitor.
fantastic.

Hope this helps at least one person
Dan