Had 1200 mile svc at dealer yesterday on 07 M Roadster. On highway tonight at 80 mph, heard a whine from rear, then a thump, then lost about 20+ mph; pulled immediately to break-down lane; lots of blue smoke came from the rear-end when I stopped; I assumed I had a flat. Instead, after flat-bed arrived to tow, realized that all tires were fine but rear wheels were frozen and would not turn. Had to drag it up onto flat-bed even though in neutral, with engine running, with clutch fully pressed. any thoughts?