The error reason 1048 seems to indicate a problem validating the signature on the host server certificate. That is why I worked on getting Adobe Reader to recognize my signers as legitimate signing authorities. It seemed to make no difference. For now, I must resign myself to not using shared reviews because too many of my colleagues use the Mac. So far, no one out on the message boards seems to have run into this problem. When someone solves it, I will post the answer here.