'SAFE' means that the radio is locked, this is the anti-theft mechanism. If the radio has lost power (battery disconnected?) for a reasonable length of time, then it will forget it's activation code and go into safe mode.
If the radio came as standard with the car, then you should have the code in the vehicle handbook (mine has a separate section for the radio). If you don't have the code, then you need to contact your local VW retailer, they can reset the stereo for you for a reasonable fee.
Rob, July 2007
