The switch gets older and more resistant to magnetic forces as the machine ages, so moving the magnet closer to the switch pulls it closed, making the machine detect a closed door.

An image by Mr. 680x0, and I hope I can post this... http://i12.tinypic.com/6h2lxrn.jpg

So finally the machine detects the case state correctly, it sleeps and it works... I checked my machine for the same issue but mine wasn't affected.

Case Closed. (Pun Intended)