XBMC services stops to work when idle

[kaladont]

Hi guys,

I have installed xbian on my raspberryPi. When I change source on TV and leave it
for some time idle when I swich back to xbian screen is blank. I thought that it is maybe
screen server but then I connected to raspberryPi and could see that xbmc service is stopped. Last night I left navi-x to download some movies and in the morning same thing. Why is that? How to prevent this?