Digging into this a little more, it looks like there may be something problematic in the database. Looking at what config diagnostics I can and searching for answers, there's a reported fix for vBulletin 5 that *might* work if it's not a database corruption issue - increasing the execution time and the memory limit in config.php. (The recommended values were 2880 and -1, respectively). But when I go into the language manager and look at any language's phrases, they all appear in Polish rather than the actual language they should be (I checked English, the attempted Spanish import, and French). A "rebuild all languages" might help, but I don't want to do that until I know both (a) we have the xml files for all languages for recovery, and (b) that we have a good backup of the database in case things go really off the rails. I'm trying to remember who it was who helped with the migration from the Provo data center (Per, was it you?).