Fail to target the windows

Hello there,

I have an issue when booting up COS.
Everything runs smoothly, but when I come on the desktop, I need to log out/log in a few times to fix this bug:

When I have the focus inside of the window (I can click on the buttons & stuff inside of the window), I can't click on the close/minimize buttons, and I can't click elsewhere too (So no desktop, no other windows, no start menu), but when I have the focus on the border of the window (with close/minimize buttons), everything is good, except that I can't interact with the window itself, only the 2/3 buttons on top.

I've been experiencing this problem since Ubuntu 13.10 (And that's the main reason why I quit it), and since everything seems to run smoothly for the others, I'd want to know if anyone have the same problem, and how to fix it.

Thanks in advance !