need help 2000 525i

my 2000 528i has several problems ive noticed, my abs and brake lights are on , then this other light is on but i have no idea what it is , it has a triangle inside a circle with an (!) inside the triangle , what is that ? ...... also at low speeds theres rough feel to my car like grinding when i brake or my car going about 5 to 15 mph ... i had new rotors installed in the front, new pads on all four wheels, and still nothing has changed ,, the mechanic said i still have a litlle bit to go on my back rotors but i dont know if he really knows what is going on ... thanks for any insite yall can give me with my problems... i want to be prepared when i go to the dealer ..