Bill:
A while ago, I had what sounds like the exact problem you're having now. It turned out that my Alk. was too high and Ca. & Mg. too low. After correcting the balance, my corals stopped dying off and began to flourish. I shut my Calc reactor down for a while and added Turbo Calcium and Mg daily until I got everything in balance.
Bringing the salinity up slowly is good, but IMO you need to get the Alk/Ca/Mg in balance also.