sky sucks - I've got it and it keeps crashing. Things to try...
1) if possible, move your PC or ariel around a bit to see if the signal gets better (but to be honest, unless you're a severe distance from the router then this shouldn't be your problem)
2) right click the little "computer with green waves coming out of it" icon in the bottom left corner, select "repair", and wait for 30 seconds for the connection to reset - it might come back stronger.
3) unplug your router (box that's plugged into your phoneline), wait 30 seconds and plug it back in. 30 seconds later your web connection should be reset, and might be stronger.
4) call the sky support line - they can sometimes actually be helpful
5) check your microfilters (the little box that is plugged between your phone line and your router) by plugging in your spare (if you have one - if you don't Sky should have given you 2 spares when you had the system installed, so phone to get some)
6) get a new router - ours is less than 12 months old and is dying. We should be getting a new one (freee) of Sky this week, but only after arguing with them for a while