This is a known problem, for which Volvo has issued a TSB. Drive shaft shudder when rolling from a standing start, especially when the car is heavily loaded. The geometry of the drive shaft changes under torque from the standing start and/or from changes caused by a heavy load. Very minor adjustments (like, the thickness of a single washer as a spacer) to the center support bearing of the drive shaft can have substantial effect on the drive shaft shudder.

Check out this thread for more info.

FYI: if you remove the shaft for any reason, be sure to mark it so it goes back in exactly the same configuration as it was originally; i.e., keep the same bolt holes on the shaft flanges aligned to their same respective original counterpart holes.