Andrew,

I looked at your model. There's nothing wrong with it. I can not get it to display any screen anomalies, as depicted in your posted image.

So, it's apparently a display anomaly attributable to your graphics card or OpenGL. I note that you've updated the drivers, but that may not resolve the problem.

I run SketchUp on a 6-year-old DELL Inspiron, and am using 5-year-old drivers. I have no 'major' display problems, however, I've tried newer, updated drivers. The newer drivers actually caused HUGE problems! So, the newest drivers aren't always the best.

My recommendation is to collect as many of the driver revisions as you can, testing each one. Stick with the best performer, no matter what comes along later. (If it ain't broke, don't fix it.)

I hope this info eventually helps to resolve your problem.

Regards. Taff