error while using brightness function

hi fedora team, 
i am using fedora 20, on my dell n5010 laptop. it has 3 gb of RAM and
500 GB memory and works on 64x architecture. i am loving this new linux
environment, everything is going fine, except a few things.
like....while i try to control brightness, the system gets hanged and
stops functioning. Similarly it happens when, i try to open a new
function or app.