Random channels just stopped working!

Hi guys im a newbie and dont know too much about the Dreambox. It has always been giving me problems - like all the channels go blank and i have to restart. But now for the past 2 weeks more than half the channels just have just stopped working. Not any particular group but all very random like ITV1, ESPN, E4, Movie Channels. While others are still working like BBC1, all the Sky Sports Channels.

PLEASE HELP