after i minimize and/or when a message from my computer pops up,and i return to the game,the whole screen is a little darker?

ok so i've had this problem since like...always since i downloaded the game. i use windows 7. i had that problem the first time i downloaded the game (and after 2-3 months i had to delete it and redownload and re-install it for some reasons and now i still have it)


so basically any time that something interrupts the game from playing it (for example when i click the windows start-menu button,and also when i close the laptop -not turn it off- ), when i re-open it (not from the beginning,i mean when i click the icon and i open the game from where it was left) everything is a shade darker. i tried changing the settings for a lower resolution,i also checked it i had to change the lightness or something like that. the problem is still there
any suggestions? maybe a new mod or something like that

ps sorry for my English, and im a nood so please explain your answer
thanks:)

I used to have this problem on my laptop, I think I still do but I used to just work around it by when it got darker, I would just minimise and maximise  a lot of times and it would sort of fix it by returning it back to its normal brightness. This worked someday but not all.. I dont know how to fix this but maybe you can try it and see what it does for you?