Originally Posted by Asmodean
As other have said, overheating could be causing it, its not as stable as you think, or maybe the power supply is not sufficent for the new clocks, as its a laptop.
It's why, even if the laptop has a good fan system, it's not worth overclocking. Laptops are designed with the smallest requirements in mind. The "power supply" is a very good example. It is designed specifically for the laptop and what should be it's max usage with stock parts. The problem with overclocking a laptop fits in this list : very unreliable, very unpredictable overclocks, subject to heating issues even without an overclock, most likely to have voltage supply problems past stock, there may be performance bottlenecks in the laptops main-board that would be unforeseen as most manufacturers will squeeze as much as they can out of a series.. This list has so many reasons NOT to overclock a laptop it's ridiculous, it's simply not designed for it. I would even argue an Alienware ( now owned by dell ) would be an example of a laptop not to overclock.. the video chipset on the mainboard is most likely going to be pumping the heat, if not the added hard drive.
Do yourself a favor, don't overclock a laptop, you are far more likely to damage it in the process than with a desktop, or keep the performance the same with worse efficiency.