Hi Tracey.
My Sky plus got screwed up just like that every time it was put into 'stand-by' mode because of an incorrectly programmed update transmission from Sky but I found that I could get it working again if I rebooted the box and stopped it going into stand-by.
Switch off the Power Supply.
Wait a minimum of two minutes before switching back on again. After about 15 secs the box will respond to the remote and try the box functions again.
If all fails, don't throw your money away on a Sky engineer. They dont mend boxes and you dont need to spend £65 just to be told 'I'ts ad it luv'.
There are loads of Sky + boxes on Ebay where people have upgraded to HD
cledlyn
June 2009