So to be clear, these lines do not disappear on their own after a second or two, but persist indefinitely until you do something like shut the unit down?
Have a 2009 Macbook recently updated with Lion, 10.7.4 and all updated software, This includes a very recent update of Lion that Mac support helped me install. I was having several problems with my Macbook (which just came off of Applecare policy.) All has been well for about a week. Then one of the original problems started again. Once I engaged the cursor it made a small black tile on the screen that continued a linear track where ever I moved the cursor to. I could make an arrow or ball or whatever with it. But It also wiped out anything it touched on the screen and eventually all would become black. Once I pushed the off/on button to turn it off, and removed the battery for a minute or so, and turned it on again it's o.k. But I'm concerned this will happen again. Suggestions?

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