Alienware M17xR4 keyboard problem

Hello,

I have some sort of keyboard problem. I am using Delphi so it is necessary to me to type CTRL+SHIFT+S from time to time. It wouldn't be a problem, but when I press F12 key, my computer goes into sleep mode.

I tried pressing F12 before I type CTRL+SHIFT+S and its working fine, so the problem occurs after I type CTRL+SHIFT+S for the first time.

Is there some way to disable this, or will I just have to find a way to live with it?

Thank you, Leon.