Same thing happened to me AYG. My laptop was over heating and cutting out, (and I know its full of crumbs because some of the keys are stuck!)
If like me you use it on your lap or sofa, it will heat up quickly. I bought a laptop cooling pad for about a tenner and its worked a treat. Something like this but there are loads of types. You just sit the laptop on the cooling pad and it fans it using a connnection into the laptop. No extra mains needed.
Try it, its a whole lot cheaper than a new device.
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