Windows 7 grey filter on screen

[montgomery]

Hello,
I am experiencing a nuisance issue whereby on depression of the shift key or after a time lapse my screen background changes from near white to grey. I can rectify to screen colouration by switching the monitor off and then on, but this is not the answer. Can anyone help?

 

[soundguruman]

Did you try another monitor?

 

[edmond419]

Try lowering your screen resolution or changing monitors or your computer's PSU

 

[fowang]

could be some sort of power save setting