What kind of laptop is it? How old is it?
What software are you using?
I'd be interested in hearing the answer to this as well. If it's an older machine and you've never opened it and cleaned it out that could explain the problem. It could also be that the fan is clogged or even non-functional, a friend of mine had his notebook fan die on him this summer and the machine was only a year old.
As others have said running hot when processing graphics is not uncommon. On one of my notebooks, a MacBook Pro, I installed a temperature monitor and was astonished to see that some of the internal components get as hot as 98 degrees Celsius - that's only 2 degrees below the boiling point of water! This usually happens when I'm processing video with Final Cut Pro, I also just installed a new graphics tablet on this machine yesterday and I see that when I draw on the screen the temperature goes up dramatically. You can hear the fan in the Mac kick into high gear when this happens and it quickly brings the temperature down below 60 degrees Celsius.
If you're curious you can also install a temperature monitor. The one I just spoke of is for the Apple and is called (amazingly enough) "Temperature Monitor". It's a free download from the Apps Store.
For Windows machines you can try Core Temp, a free application you can download from
http://www.alcpu.com/CoreTemp/. I've used it on a few of my Windows machines, it's a bit challenging to configure but if done properly it allows you to actually change the temperature at which the computers internal fan is activated. This might be very helpful for you as you could have your fan kick in at a lower temperature to keep it from overheating.
Linux users have a bit more of a challenge, but we're used to that! I found a good resource for installing a Linux temperature monitor at this site -
http://www.cyberciti.biz/faq/howto-linux-get-sensors-information/ . I'm planning on trying this on my Ubuntu workstation, although I don't really suspect it has any problems as it seems to run pretty cool.
Hope this helps, again please let us know the details regarding your hardware so we can be of further assistance.
Bill