|you need to get a laptop cooling pad for starters, then take a cover off the back while it is on the pad so you can cool the laptop down. you can then download a program called speed fan. its free just google it.|
You will then find out if the processor is running hot or not (60-100C). if it is hot then it could be the heatsinc, i had a similar problem with mine, i took the heatsinc off to replace the thermal paste and clear the fan out (which hopefully thats all yours needs)
Try that first, if not let me know and i will tell you the next step.
Hope this helps