When I was zooming into an object of the sudden the scene view got gray but, the game view didn’t. I have a macbook late 2008 2GHz Intel Core duo 2 processor 2GB of ram and NVIDIA GeForce 9400M graphic card.
I fixed it myself. THANK GOD.
What was the solution then? If someone else have, or will have, a similar problem. 
The solution was add a new scene view tab and close the old one.