The last 2 times that ive started the car (car sitting out in the cold overnight), its made this loud screatching sound, almost like rubbing her nails against a chalkboard kinda sound. Sound lasts maybe 5 seconds and then goes away. Any idea what the prob could be?

car is a 1990 audi 90, fwd
Thanks

none of this happened a few months ago when it was warm out..still, i dont see my other car doin this, so i imagine what ever it is, it must be fixable.