I have a Humax HDR-1000S which at standby is showing the clock. Sometimes when I switch it on, it gets to <free time> and then goes back to the clock. When it next powers on OK, it's not showing a picture or sound, and the guide is empty. Why might it be doing this, how do I get it to stay on, or is this a known fault? (It all worked OK with a (now dead) Sky+HD box.) Thank you.