All right...here is another one. This have happened four times sence I started working my waythrough the Pro Animator tutorials. What I'm getting is screen studder, a flashing on and off of the screen elements, within the applecation. This seems to happen most offen within the Invigorator Text tool, when I'm trying to change some aspect of the type. This will also vibrate the icons on the desk top. the only way to get out of it is close the application, and of course, it does not let you save. This time control-alt-delete and then end process was the only way out.
I remember one other person had this problem and it went away once he updated the drivers for his video card. Try this first. If this doesn't work let us know about the hardware you are using.
This kind of thing can also be caused by "desktop optimizers" which are part of your video card control panel. Such as the "screen panning" "xtra large screen" "virtual screen" and other screen management features. Try turning off all of these extra features and see if that clears up the problem.
Another thing that sometimes causes trouble is the driver for your input device. If you have a tablet or a special kind of mouse turn it off or use "normal mode" and test to see if that clears things up. Once we've isolated what's causing the trouble it may be easy to fix or find a workaround.