What kind of TV do you have? Is it a Philips TV? According to the main DN2820FYKH thread, the early Media Center Remotes (which the NUC is designed to respond to) were made by Philips, and some of the IR codes are similar. I have a Philips TV, and my Philips TV remote will turn on my NUC when I try to turn on the TV. If I turn on only the NUC by remote, it does not turn on my TV.
I haven't found a proper way around this situation, unfortunately.
EDIT:
http://www.amazon.co.uk/o/ASIN/B001HNH1WE?tag=adapas-21
Okay, it looks like the Sky remote is made by Philips. That's why the Sky remote turns on your NUC. I think the simplest options in this case are to simply live with the problem (if it's not a major annoyance), or to replace your Sky remote with another universal remote made by a different company (assuming you don't have a Philips TV). I recommend the Logitech Harmony series if you're looking to switch remotes.
Second Edit: Okay, I re-read the original post and just realized the OP is referring to a Sky set top box, used for watching TV. I'm assuming that box is manufactured by Philips and shares the same PowerToggle IR code as the old Philips Media Center remote controls, which is what the NUC is picking up. At this point, I'd say that there isn't going to be an fix to this situation, except for getting a different brand of TV box that isn't manufactured by Philips.
(2014-03-12, 12:16)jinkyjim Wrote: Hi, do you have a FLIRC USB dongle on your nuc ?
it would do that..
Most people aren't going to buy an FLIRC for the current generation NUC models, because they already have a built in IR receiver. It would be quite redundant and unnecessary for most people.