Mine sometimes floods out when the filters get blocked - it also happens when the level indicator valve ceases to work through debris. You can find the level valve in the dishwasher, usually on the bottom bit where the element is, it's round and looks like it has a cap on it the size of a pop bottlelid. It needs pushing up and down and freeing if stuck, taking a bottle brush to it usually works. Also try using one of those dishwasher cleaner pruducts - did a good job on mine.