Graphics glitch

[eatcake]

Hi
I have a graphics glitch where the bottom half of my game is (it's not stuck to my screen) with skyline it changes color when it's day(white) or night(dark blue/black). This wasn't always this way, it happened within the last month. I've played in both windowed and full screen mode and adjusted various settings and it's still there.

PC:
g3258
radeon 4890
8gb ddr3

Pic
[url=http://www.upload.ee/image/5391625/12346846_10207102157024781_151978282_n.jpg][img]http://www.upload.ee/thumb/5391625/12346846_10207102157024781_151978282_n.jpg[/img][/url]

[url=http://www.upload.ee/image/5391622/12355806_10207102170585120_1975398157_o.jpg][img]http://www.upload.ee/thumb/5391622/12355806_10207102170585120_1975398157_o.jpg[/img][/url]

[url=http://www.upload.ee/image/5391617/12369503_10207102171545144_229673788_o.jpg][img]http://www.upload.ee/thumb/5391617/12369503_10207102171545144_229673788_o.jpg[/img][/url]