It turns out that PTX update wasn’t working on my machine because of some incompatibility with SIL fonts. (Thanks, John+Wickberg, for finding this!) First the log file showed a problem (1603) with the DoulosSIL-R.ttf font. Deleting it was a bear! I couldn’t do it through Windows and using the command line just gave me “Access denied” messages. I finally managed to delete the offending font in Safe Mode. Then I got the same message about the Charis font. This time I got the latest versions of those fonts from the internet and installed both Doulos & Charis sets. I ran the installer again, and it returned error 1603 again. This time it was the Galatia font set. Once more, I got a newer version of the fonts from the internet, and installed them. The third time was the charm. Glad to report that I now have Paratext 8.0.100.72 up and running. But, the question remains, why would Paratext updater have problems with SIL fonts to begin with?