sky box will not turn on

[dave123456]

we've had a sky+ hd box for about 7 months, it's never been perfect but just recently it turns itself off and either takes a very long while to restart or won't start at all.

it is connected to a tv in the sitting room via a hdmi cable (on a splitter with a dvd, there's only one cable in the wall to the tv) and a tv in the kitchen via a magic eye.

any ideas why it won't just turn on?

thank you

[dave123456]

ended up a stage further.

turned off at the mains,
hold down the left and right arrows either side of the reset button,
turned power on whilst continuing to hold these down,
continuing holding them down until the blue circle lit up,
hit reset
waited for about 20 mins and then it rebooted

apparently you lose everything if you do this, but I had no settings or recorded stuff anyway.