Possible causes
Float switch is jammed or malfunctioning - solution: Clean float shaft so float moves freely. If necessary, replace float switch.
check this link
http://www.ehow.com/how_112264_correct-overflowing-dishwasher.html
Machine isn't level - solution: Adjust feet to level machine.
Broken door gasket - solution: Replace gasket.
Loose hoses or fittings - solution: Tighten hoses and water-supply-line fitting.
Pump or motor seal leaks - solution Call a professional.
I hope it helps
Deeky Evans, December 2004