Project window loses focus on stop

AN intriguing issue yesterday

I opened a project which was fine previously, but this time,
on pressing stop via comp keyboard space key, the project window loses focus,
meaning that I have to click in the window before N7 accepts further key input.

Remote controls still work as normal. But this is seriously disruptive!

Any thoughts?

So why would this be?

This problem still persists…
I have two projects side by side in N7.
One behaves itself correctly - the project window keeps the focus, so I can perform multiple PLay/Stop/Rewind/FF functions and each works correctly.

THe other has randomly changed its behaviour - after a keyboard input, the project window loses the focus. Now keyboard input does not work until I click on the window, when it regains focus, but only until the next keyboard input…
Anybody have any thoughts on this conundrum?