Those rubber seals are bastards sometimes. Make sure it's clean and straight. I don't know how many times I've had to reinstall those due to slight misalignment or small debris under the rubber gasket. Torque is a HUGE factor with rubber gaskets as well. Make sure those babies are torqued right down to spec

Check on the bottom side of the engine near the crank pulley, sounds like it could be dripping from the backside somewhere onto the belts making it fling everywhere.