one of the most common leaks i see in that area is from the drain tube in the pillar. if your sunroof is factory it has a tube at each corner. these tubes direct any water that gets pass the seal down into the body and out to the ground, the front tubes run down the apillars and into the kick panels. these tubes are known for getting clog with dirt and then leaking into the car.
if you lower the headliner youll see them take and disconnect them from the sunroof and blow air through them to clear them out.
what year is your pt cruiser ?