I'm having this problem since I got Ubuntu 13.04 (few weeks ago). At random times, when using gnome-screenshot, I get a gray image. It doesn't work until I restart my computer. I've tried getting GNOME 3.8 (it was a very bad idea), but it didn't solve the issue. Some other applications that capture screenshots (Screencloud) have the same issue. Here's the gray image I'm getting. I've searched everywhere, but I couldn't find an answer.
My specs: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) RAM:2GB Type of computer:Laptop.