I have to ask...are your drivers the latest version?
There are two ways to troubleshoot this. The easiest way is to turn down the settings about 75% of the way down from the game launcher video ooptions. See if it is OK. If it is, turn up settings a bit at a time then go back into the game to see if the lines are back. Once they are back, set it back a notch and you will be good to go.
The other way is to turn down one setting at a time. But not the general high or very high in the game launcher. In game, there are more video settings. Try turning down anisotropic filtering a notch. If nothing happens try to turn down the antialiasing a bit. And so on. Only change one thing at a time. Keep notes of wat you're changing each time.
It looks like it is a rendering issue and anisotropic setting may be the culprit.
EDIT: another idea is to turn down the screen resolution bit by bit too. Maybe try that before messing with the graphics settings.
Edited by Dacar92, 10 May 2013 - 08:26 PM.
What's the point in being grown up if you can't be childish sometimes? -- The Doctor