There is many possible reasons why this happens and first thing would be to unplug everything you can around the house and see if that makes a difference. If not change the fuse in washing machine, and after doing them 2 things the problem still continues then I've not really any more suggestions apart from getting a sparky. (if council tenant, ring your council now and you will speak with out of hours repair team - and all you need to say is something like, you can't have electric appliances plugged in because it's tripping your electrics and it will be classed as an emergency and someone will turn up within 3 hours depending on how busy they are)
Simon
April 2010