Screen tearing happens because of refresh rate miss matches between the video card and the monitor. Make sure both are at 60Hz.
Make sure the video card drivers are up to date.
If the problem persists, you might want to hook up the laptops to an external monitor.
You might try to turn on triple buffering on the video card, but I don't know if melty supports it.
The only other solution for tearing that I know of is v-sync, which sounds like a terrible idea with melty.
-NC Texas Tim-