Why does my Servis fill with water overnight?

My servis automatic 600 has no problem with washing clothes. When it completes a cycle the cloths are clean and the drum is dry. However, by the morning the drum has filled with clean water(no sign of dirty water) and if I don't leave the door closed, floods my kitchen. If I close the door and do a final spin cycle, the water drains and the drum is dry again.
Any idea as to why my machine fills with clean water overnight and how do I repair it?