Why does my Hotpoint Ultima 1000 say 'close door'?

I have had the same problem. Also F-05 error messages on and off since I bought it. The service man says there is a glitch with the door circuitry and has already had to replace this door lock unit. I also remember it being 'live' at some point. Am going to have to get a warranty because it keeps going wrong. Kind of a blackmail warranty offer I think, we are held hostage to bad design. I wish I hadn't bought this brand.......

Amelia
August 2006