If the vehicle cannot return to run position after start or if the interior fan is not getting power, it may be the electrical portion of the ignition switch has become erratic or has failed. The entire switch assembly should be replaced.Google+
Car Problem Reports
Porsche Boxster Electrical Portion of Ignition Switch May Become Erratic or Fail
Porsche Boxster Problem
Average Mileage: 50,600 mi (25,000 mi - 79,000 mi)
Visitor, 2000 Porsche Boxster, 47,000 mi
I had the same problem. Although I could turn off the engine and remove the key, turning the key as difficult and neither the fan or windshield wipers would operate. Replacing the switch resolved all the problems. Access to the two mounting screws is tricky. I suggest using a screw driver used for eyeglasses, flat blade, 2 1/2 inches long. Replacement of the plastic ductwork requires patience as the mating end by the door drops. Pay attention as this end is not rectangular and will only fit one way.
Visitor, 2003 Porsche Boxster, 65,000 mi
I changed out the switch to resolve the issue
Visitor, 2001 Porsche Boxster, 69,000 mi
Key can be difficult to put in ignition, headlights are dim, bright lights don't work, wipers quit working, radio sometimes stays on indefinitely after car is turned off.
Visitor, 2003 Porsche Boxster, 25,000 mi
Ignition switch would not turn nor release the key, engine ran in the off position-replaced ignition switch