wrote: Hi
Sky are moving away from all browser's including Internet Explorer because Silverlight is no longer supported by most of them, for that reason that have now released a desktop app that can be used instead that doesn't need any browser for it to work.
You can download it from Sky here
When you go to use it, it will register as a new device despite you installing it on a PC/Mac that was used before, this is because this new app does not use Silverlight so you might need to delete a device if you do not have a spare slot.
ceasarome is correct. However from personal experience if you already have the maximum of four devices registered you will be told that you can only change a registration once per month. i.e. you will have to wait a month before you can register a new device having removed one. Courtesy of rscot of this parish for the information if you call Sky on 03442 414141 and explain you have removed a registered device because you were compelled to download and install the new Sky Go or Sky Sports Player etc they will free up a slot for you. This takes about 15 to 20 minutes to update your account from which point you can launch the new Sky Go, or whatever app, which will register your device and ............... happy days 
I sincerely hope this helps because it’s very frustrating but it worked for me. I’m cream crackered atm but I hope to write up a full fix walkthrough tomorrow based upon my own experience with VERY MUCH help/advice from some extremely patient folk on this forum.