Unresponsiveness

Sometimes when i boot into Windows 7, either the trackpad or keyboard will not work without a reboot. Also, the screen will sometimes default to minimal brightness, and the F1/F2 keys won't increase the brightness. The sun image will come up and the bars at the bottom will move, but the screen will not change in brightness, and since it's so dark, i cannot see anything without a flashlight. What's the problem?

Thank you to whoever fixed the title.