TS4: half-screen render issue.

I just installed ts4.2 on my new HP, and I have also noticed this problem on a friend's computer: whenever I render anything it only renders in the bottom half of the screen. Example: if I have a sphere right in the middle, and render the object, only the lower half of the sphere appears. But if it's below the half way line it renders fine. Do you know how to fix this?

[pcmacman]

Just an idea, but does TS support multi threading? Maybe theres some setting that was accidentally changed that somehow is messing up the rendering....