Oldsmobile/Buick Repair: brakes locking, oldsmobile cutlass, rear brakes

Question
After I had a friend of mine replace the brake system on my 1991 Oldsmobile Cutlass Calais, I have had the problem of them locking up from time to time.  My car will still stop, but it goes down slightly, and skids slightly and makes a screeching noise.  It only happens some of the time, usually when stopping suddenly.  I took the car back to him, and he bled the brakes again, which didn't help.  I then took it to a mechanic and they said that the back brakes hadn't been cleaned properly, so they cleaned them, and that didn't help.  Do you have any idea how to fix this problem?

Answer
Hello lena

this is a brake adjusment on the rear brakes . the one sid is to high and the other side to low bring to a good brake shop and tell them to adjust the rear brakes this will solve the problem you are haveing . good luck to you hun and you have a pretty name pete