Black lines on top and bottom of my screen in L4D

[kokoman90]

I have really weird problem in Left4Dead2
It worked just fine yesterday. I logged in into Left4Dead2, and I have black lines on top and bottom of my screen.
I am using recommanded resolution. It looks somthing like that:
http://i.imgur.com/XWUq3.jpg ( I edited it in paint because I dont know how to take that picture in-game)

If I change the resolution to 1920X1080 ( Like my desktop resolution) the game works on full screen without the black lines, but it look suck. The picture looks like it stretched.
I think this issue is because the Windows update, but I am not sure. I am using Windows-7

How to solve this?
Thanks!

 

[PP Mguire]

The lines are there because you aren't in a 1080p resolution that is native to your monitor. It looks like you may have the film grain effect turned on. Try turning that off and putting the res back to 1920x1080.

 

[kokoman90]

The lines are there because you aren't in a 1080p resolution that is native to your monitor. It looks like you may have the film grain effect turned on. Try turning that off and putting the res back to 1920x1080.

I turned the film grain effect off and there is no change. If I change the res back to 1920X1080 all the screen isnt feet right. it looks suck.

 

[kokoman90]

anyone?

 

[PP Mguire]

The game doesn't look very good as it is. The only way to get those lines to go away is to set the native res. The only other thing I can think of is just make sure film grain is off and have the settings turned up.

 

[kokoman90]

the film grain is off. i didnt see any difference with that lines if its on or off.
i dont understand why that happened, it worked for me 2 days ago with recommanded res, and now its not. whats wrong with it?