Hammer screen flicker!

[didier.c]

Recently i am having trouble with Portal2 authoring tool or Hammer; When i try to use it the screen starts flickering between Hammer and my desktop, rendering all work impossible.
Sometimes all 4 screens go dark and the Hammer logo at the bottom of my screen keeps going back and forth as if loading again and again!
I am fairly sure its not my computer as it was running fine for years up until a month ago or so.
I have windows 7 professional.
Please ,if anybody knows how to fix my problem, speak up!
Thanks.

[Dmitriy]

probably because some software you installed recently. May be screen recording soft. My be new drivers

[didier.c]

If so, how do i pin point the issue?

[Dmitriy]

Well if you installed Fraps and hit F9 it will record Hammer screens

[Dmitriy]

I'm not sure about other software's hotkeys

[didier.c]

No ,but thanks ,i will try to remember if i did anything to my computer but as far as drivers, well its done automatically, so iam not sure where to look.
I am thinking about going back to an earlier recovery point.

[ALWAYS COMMEND]

i disabled nvidia overlay to fix