Jim, I went the other way. I had already reinstalled 3.4.23, so I opened it, deleted my single Star model (that I don't use), exited 3.4.23 to rewrite the XML file.
Installed the 3.4.24 (not the debug version). It runs just fine now.
Will now install even newer versions.
p.s., to those who "never install new versions close to production time" Don't ever ask to be Beta Testers. A Beta Tester will install new versions even if there is a HIGH PROBABILITY that something won't work.