You should flash the box with a standard Dream-Multimedia image available from IHAD(_www.i-have-a-dreambox.com 'database' area). You should also check,if possible, whether the problem is still there after doing this. I realise you might not be able to see the channels you would normally watch, but try one of the freesat channels.
You should remove the hard disk. If you fit it in the 'new' box, all that was there before will still be available. If you don't remove the disk, you might not get it back.