It may be that you have got oil or grease impregnated in your pads, only way to find out is to replace them, not a bad idea anyway if they are worn, make sure as other people have said that the sliders on the calipers are free and keep those greasy hands away from the new pads. Also if you fit new discs these come with a protective layer of grease to stop them rusting and must be cleaned with petrol before fitting or you get squeaking probs.
