If you are saying that the drawers are on metal runners and that they slide back open when closed then the cabinet may be leaning forward. You can either level up the cabinet or lean the runners so that they are pointing up slightly. To do this you need to remove the drawers and take the rear screws out of the runners into the cabinet sides. Also any middle screws if there are any. Then drill new screw holes slightly lower than the original ones and reassemble. Hope this helps.
Dave of Bexleyheath, September 2008
