2002 Pontiac Aztek Brakes skipping and grinding

Brakes problem
2002 Pontiac Aztek Automatic 85000 miles

Whenever I'm making a sharp turn at a slow rate the brakes start making a grinding/crunching noise and they don't work. The car basically skips to a stop. One time when this happened the ABS light went on but then turned off later and I haven't seen it since. It only happens every once in a while. I took it to the dealer and they drove it around a while and it didn't do it so they said they couldn't fix it. I did get new rotor and brake pads a year and a half ago.