In the heatwave of a few weeks back, laptops had to work even harder than normal to keep cool. I had a Toshiba Satellite L300D come into the surgery, suffering from overheating and intermittent shutdowns. Just touching the base of the machine after it had been on for a few minutes proved there was a problem. It was extremely hot to the touch!
Stripping the machine down soon highlighted the problem. The cpu fan outlet was literally blocked with dust. There was nowhere for the hot air to escape. No wonder the poor fan was working overtime.
A quick clean up, combined with a few squirts of compressed air cleaner and everything was as good as new. Once the machine was reassembled, it powered up first time and was good to go.
Try to help your laptop keep cool by remembering to allow room for air to circulate freely around the case when its on. Ideally, pop it on a stand to use when you can. Remember, the cooler it runs, the longer the internal components are likely to last and the more reliable your machine is likely to be in the long term.