Just repainted a room last painted 35 years ago and now have a peeling problem, The room color was white and constructed of drywall 30-35 years ago. I painted over the white with a good quality platinum colored latex paint and after the second coat noticed some checking of the surface. applied a scraper to remove the checking and the paint peeled off in large pieces. The chips have a white coating on the back indicating the latex is adhereing and the old coating is releasing. Any ideas?