I had 3 in a row that did that, when I bought my laptop from PC World early last year. Im on my fifth now (all done under guarantee within 10 months from parting with my money), they had many reasons they gave, none of which I actually believed, as I used to work as a microelectronics tech. I got some of the biggest BS I've ever heard. Best thing to do, is if your laptops still under guarantee, take it back to the shop you bought it from, get it swapped, and keep going until you get a product you are happy to keep.