I have my desktop on all day but shut it off at night, mainly to not have something on when it isn't being used.

I don't like leaving a laptop on for that many hours, just in case.

I guess it depends on how much it bothers you, if you don't want to mess with it until it gets worse or not.
But I would copy off any important files to a flash drive or cd. Just in case it totally fails at some point.