We came to the conclusion it's the strength of the internet signal. Our Wifi dropped out with monotonous regularity sometimes just seconds, sometimes a couple of minutes. It was worse the further away from the router the 'puter was. My iPad was the touchiest. Sit next to the router and no problem. At the back of the house, furthest away it happened frequently. We bought a booster (£35) to plug in half way and things have improved considerably. Worth a try?
Twice in the past week one of the laptops in the house has suddenly lost wireless internet connection. Unplugging the router and plugging back in works. The odd thing is all other devices continue to be connected when this happens. One of lifes mysteries or a problem with the laptop??