2002 Jeep Liberty HELP!

LONG STORY. Back in october I had my brakes done. When it rians the front wheels lock and make this metal on metal noise. I brought it back to the person who did the brakes - they couldnt find anything wrong. I brought it to the dealer and they couldnt find anything wrong. After a couple of dry months the rain started and the locking and noise was back- I went back to the dealer - it locked for them but they couldnt find anything wrong with it STILL. So I had them replace the brakes (about a month ago)- well it rained today and its worse - locking, tires sliding and the noise is loud. I am pertrified to drive the car in the rain. I am at my witsss end - please help - any ideas to what is causing it? Has anyone else had this issue?