I have been having probs with the rear calipers for a while now. I knew the calipers were shot, causing the brakes to bind. At one point the o/s/r disc was glowing red!
I got some calipers and carriers off ebay and some discs and pads from the local Partco.
Its not hard to see why they were sticking ! Heres some pics of just how bad they were.
2 Hours in the snow and shes sorted, I now have a handbrake also