Thanks for the checks! I will tentatively say that the issue is resolved.
It appears to have been the Lightbox 2 plugin that I was using (v.2.0.2). That’s the only one that I still had disabled, as I had never been able to get it to work properly.
I think the problem was an improperly cleared cache, so even when the plugin was disabled, it was still affecting IE7.
Note to others with similar problems in the future: ensure you completely clear your cache!
Still tracking down the syntax error, though ??