I have a Samsung Series 7 laptop. It has the hybrid Radeon 6750M/Intel graphics. I've been getting weird artifacts sometimes now. They even happen in Lubuntu (in VirtualBox). It sort of looks like it is rendering in low-color, but Windows 7 is set to 32 bit. Both graphics drivers are updated, and I did try rolling back as well, but to no avail. They almost always manifest as those weird lines. In addition, it is not permanent; it seems to come and go. GPU-Z shows normal temperatures, and laptop doesn't run hot at all.