My Laptop is running very hot. To the point that Ubuntu is giving me warnings. Now it's not crashing or anything. What I do notice, however, is that when I first turn on the computer I can run BBC iPlayer smoothly. As time goes on it becomes more choppy as the Laptop heats up. How can I cool it down?

I have had it run overnight downloading and it's not crashed on me ever. I just wish there was a way of cooling it down a bit.

Thanks, any wisdom appreciated.