I was in the middle of a road trip yesterday when I was cruising at around 85mph. All the sudden I hear a loud grinding noise from the bottom driver's side and then the same noise from the bottom passanger side....right after that my guage's all go all the way to the right, then all the way to the left. My car made a "ding" and then went back to normal. There was no hesitation in the car. I don't understand what this is, can someone help? I just had the alternator replaced a month ago (for the second time, the first one they put in went bad). Also, I noticed that my lights would get bright and then go back to normal every once in awhile.....is this a sign that the alternator is bad, again? Are these two things related? HELP PLEASE!!!