Only Tech Support could give the exact details, but it could be the one system doesn't have the same data as another system because they got out of sync (apparently valid user license info). Or could be one system did an update recently that is causing problems when communicating with the other system. When it comes to computers messing up, the possibilities are endless, bizarre, or even stupidly simple

Bummer you can't read your book, but you should have an answer from enTourage tomorrow given it's not past close-of-business there.