2001 Mondeo stereo 6006E error fault. Please help!?

I have recently bought a 2001 Ford Mondeo with the original 6006E 6 disc multi changer stereo in it. All functions work well with it except I havent been able to load a cd into it since I have had it, it just comes up with 'error E -'. I have asked a lot of people what this is but nobody can seem to give me an answer. Has anybody else encountered this problem or know of any way to rectify it? Any knowledge or ideas, however big or small, will be greatfully received. Thankyou.