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UPDATE:

I just rolled back the graphics drivers and it solved the problem on my laptop. I had the latest 11/20/09 driver from NVIDIA, and rolled it back to the 8/19/09 driver.
Have you tried to reboot your machine to see if those lines are still gone?
 
I almost don't have the heart to ask this, but the new 3.1 driver versions don't happen to solve this problem, right?
 
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