One problem related to engine belts and pulleys has been reported for the 2003 Porsche 911 Turbo. The most recently reported issues are listed below.
I was cruising with the family at 65mph and heard my belts squeel and then stop after 2 or 3 seconds. About 20 seconds later a low coolant light came on and my temp light was blinking. Temp was only around 195 to 205, pretty far from the red. I immediatly pulled over and shut it down. There was a lot of coolant leaking, a large trail followed me off the interstate.