it happened once before about a year ago and then again last week when the machine just did not work for twenty four hours then worked fine for a few days and now has done it again. when it does this the door locks and can not be opened. now the machine is still not working but we have managed to get the door open but, with the door open the machine is continuusly trying to lock the door. locking and unlocking even with the door open. any suggestions?