Thanks very much, Dormouse, for your interesting responses. I'm really glad you commented on the two active HeliconFilter.exe files. That seemed to me highly suspect. I don't know whether I had a corrupt download of the beta5, or whether Windows didn't actually succeed in uninstalling 4.93, though it said it had, and somehow both files were running. No, that sounds too bizarre. I've now used a restore point from earlier today to purge all aspects of both versions from my computer. The question is, what to do next. Since skwire had similar problems with 4.93, I'm no longer so sure that the problem is peculiar to my computer. I guess I should just be patient and wait to see if my message ever gets posted on the Helicon forum, and if it does, whether it gets a reasonable response. Your first message helped me realize that it's not the end of the world if I don't get to take advantage of the 50% off offer tomorrow.
Again, thanks very much.