Sleep mode when screen is raised (but not lowered)?

[ikbradley]

That is, the screen is lit & functioning normally when lid is raise no more than 4 or 5 inches high or when closed. If you lift the lid higher than about 5 inches height, it goes to sleep/or screen goes dark, lower lid to 5 inches or less again, and the screen lights up again. I don’t know if this may be a minor fix or something more complex.