Well, for me it seems that your graphics card is almost incapable of running this heavy game, as it clearly was too heavy for my GTX260, which is actually significantly better than your cheap graphics card.
Also you can try disabling sleep mode in your system.
And overall, I think playing on a laptop isn't actually a good idea at all. Most of them are completely incapable of handling big heavy games such as this one.
Considering that you have a laptop, I would also suggest you check if it overheats when you have this issue next time. This is also a common issue with virtually all laptops.