The MySQL client, server, and PDO driver are all 5.0.51a, so I don’t think a mismatch is the problem but I wouldn’t be surprised if it’s 5.0.51a itself.
Another possibility occurred to me. My code editor, PhpEd, has its own Apache server. Since I do the build in PhpEd, that server is probably still running when I log in to MODx and having two (possibly different) versions of Apache running at the same time might be causing the trouble. I can’t remember for sure, but it’s possible that every crash has come after doing a build.
Googling "pdo crashes apache" does turn up a lot of hits, though.
