This looks like tearing to me..."tearing" is when the GPU (or CPU, depending on which is doing the rendering) updates the display buffer at a higher rate than the screen refresh. So it'll draw one frame, and before the screen is done updating, it'll already be done drawing the next frame, but it sends the new image to the screen buffer anyway, causing "partial" images to show, since the rendering process is "getting ahead of itself", as it were.
Try looking for a "vsync" or "double-buffered page flipping"*option in your settings. If you're using desktop effects (Compiz), you can go into CompizConfig Settings Manager, and under General Options, in the "Display Settings" tab, check "Sync to VBlank". This will synchronize buffer updates with screen updates (as best as it can; it's not perfect).
EDIT: Since you're using an NVIDIA GPU (w/ the closed-source driver), you can use their configuration tool to enable vsync system-wide. It should be under "X Server XVideo Settings" and "OpenGL Settings". I have them both enabled on this system, and everything's smooth as butter and tear-free.