Early MK3 calipers are known to sieze, they're exactly the same as MK2 calipers

But it was only the first year or 2 of production they were fitted. Get underneath and have a look at the calipers, if they have a great big spring on the outside they're the MK2 type, if not they're MK3.
As audi100quattro says it could be the cables, if they have a hole in the outer sheith(sp?) water gets in and will freeze if the temp drops, holding the handbrake on.