I believe the problem you are facing is screen-tearing. It happens when more than one image is displayed at the same time. Basically what causes this is a gpu and monitor not having the same refresh rate. The gpu may send a new image to the monitor before it finishes displaying the current one, and therefore you see the screen artifacts. A simple way to solve this by enabling v-sync. It is sync the gpu and monitor so they refresh at the same time, but this does cause a performance lose. Nvidia's new G-sync technology does a similar thing, the difference being it uses hardware so there is no performance lost.
Screen tearing-
http://en.wikipedia.org/wiki/Screen_tearing
V-sync-
http://www.tweakguides.com/Graphics_9.html
G-sync- http://www.guru3d.com/articles_pages/nvidia_g_sync_preview_article,1.html