I have a Lenovo y560 and the screen brightness juss keeps changing on its own, i try to set it to a brighter settingand it justs lowers itself back down within seconds, the laptop is also running windows 7 64 bit if that could be a cause.

Your computer's got an ambient light sensor to detect and automatically adjust screen brightness based on surrounding lighting. You'll have to disable the setting. Lenovo has their own energy management program that has a setting for it, but I'd imagine there's something in the Control Panel (maybe Power Options?) that allows you to turn the setting off.

Thnaks the constant switching of the brightness was really annoying me.