Serious Help with 2002 civic brakes

whats up everyone I haven't posted in a while but I am having a brake problem with my 2002 honda civic ex coupe. Every so often when I brake, my brakes will grind and it really bothers me. I went to brake check and had my pad and shoes replaced, and soon after that it started happening again and when I went back they told me that every thing looks fine. can anyone tell me what is causing my brakes to grind so I can go get the problem fixed.