Scotjimland one told me the answer to that one. It's because the data is not coming in fast enough on a MI FI ,causing the data to interupt and therefore corupt the data. I think that's what he said anyway.
Windows 8 has the tools to help you use your mobile broadband bandwidth wisely, and help ensure you don’t go over your cap and incur overage charges. You can set Windows 8 to automatically switch to a Wi-Fi network if there is one available in order to limit your mobile broadband use to only when it is truly necessary, and you can manage how mobile broadband is used through Windows policies.