Volvo Repair: strange clunking noise intermitantly, metal noise, noise issue

Question
We have a 1999 V70XC and sometimes there is a loud clunking noise from the front when coasting slowly to a stop. it is a metal on metal noise. It is never there when accelerating and is sometimes there around corners. It will be silent for days/weeks at a time and then will be there for most of a ride then go away after parking for a while.  I can find no consistency.  Any ideas and is this a potential safety issue.

Answer
William, with any noise issue, we would need to have the car on the lift to inspect it.  It may be a driveshaft issue but it could be other issues as well.  Sorry but on this one, its impossible to tell you without physically hearing and inspecting the car.  Roger