There appears to be an intermitent defect with the transmission when the vehicle gets wet. when wet the vehicle lock up and not easily go into forward or reverse. this occasionally occurs after going through a car wash or when the vehicle is driven in wet weather and then, parked. after a few hours, when it is attempted to put the vehicle in gear, the transmission is locked up and the vehicle won't move. only by rocking the vehicle does the transmission loosen up and the vehicle goes into reverse. the parking brake is not engaged. this issue is mentioned multiple times on volvo related forums.