Hi,
Here's a recall notice for the TipS Cars. Not exactly what you're experiencing, but possibly related. Hope this helps...
http://www.nhtsa.dot.gov/
Make : PORSCHE Model : BOXSTER Year : 1999
Manufacturer : PORSCHE CARS NORTH AMERICA, INC.
NHTSA CAMPAIGN ID Number : 03V004000 Mfg's Report Date : JAN 14, 2003
Component: POWER TRAIN:AUTOMATIC TRANSMISSION
Potential Number Of Units Affected : 12234
Summary:
CERTAIN 2-DOOR CONVERTIBLE PASSENGER VEHICLES EQUIPPED WITH THE TIPTRONIC (AUTOMATIC) TRANSMISSION MAY HAVE BEEN PRODUCED WITH AN INCORRECTLY ADJUSTED KEY-LOCK-CABLE DOWN TO THE SHIFT SELECTOR. IF THE KEY-LOCK-CABLE IS NOT ADJUSTED CORRECTLY, IT IS POSSIBLE THAT THE IGNITION KEY WILL SNAG UPON BEING REMOVED FRO THE IGNITION LOCK OR THE SLECTOR LEVER CAN BE SHIFTED FROM POSITION "P" WITH THE IGNITION KEY REMOVED AND THE LOCKING BUTTON OPERATED.
Consequence:
IF THE SELECTOR LEVER IS THEN SHIFTED FROM POSITION "P" TO POSITION "R, N OR D" WITH THE VEHICLE PARKED, AND IF THE PARKING BRAKE IS NOT ON, THE VHEICLE WILL NOT BE SECURED FROM INADVERTENLY ROLLING AWAY, INCREASING THE RISK OF A CRASH.
Remedy:
DEALERS WILL INSPECT THE CABLE ADJUSTMENT AND, REGARDLESS OF THE RESULTS OF THIS INSPECTION, THE KEY-LOCK-CABLE MUST ALSO BE ADJUSTED. OWNER NOTIFICATION BEGAN JULY 15, 2003. OWNERS WHO TAKE THEIR VEHICLES TO AN AUTHORIZED DEALER ON AN AGREED UPON SERVICE DATE AND DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME SHOULD CONTACT PORSCHE AT 1-800-545-8039.
Notes:
PORSCHE RECALL NO. A305. CUSTOMERS CAN ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION’S AUTO SAFETY HOTLINE AT 1-888-DASH-2-DOT (1-888-327-4236).
Happy Motoring!... Jim'99