WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Checking Drive Shafts
Courtesy of VOLVO CARS OF NORTH AMERICA.
Check that the drive shafts are locked into place in the differential drive by carefully pulling at the drive shaft constant velocity joints. The drive shaft should stay in position.