Problems with window Mode Gamma

[Maelonic]

So before this last weekend i was able to change the gamma in windows mode as that is what i play in so i can look up stuff on the webs while playing.. and for some reason out of no where i have not been able to change it.. only in full screen mode which i don't want to play in. I can be in windowed mode and turn the gamma up all the way but it don't change how dark it is at all.. and now it seems that I am forced in to playing in full screen...

if anyone can help me fix this what would be great! TIA