Thanks for the response.
I am running the latest versions of everything.
I don't think it's a theme conflict - it may be a ddsmoothmenu conflict though.
The only console troubleshooting I've been able to see is that when I have the testimonials plugin active I get a new error:
Uncaught TypeError: Property 'undefined' of object #<Object> is not a function
And it hits (adds/increments a new error) every time I scroll.
ddsmoothmenu also shows an error:
Uncaught TypeError: Cannot call method 'children' of undefined
Any thoughts? This may well not be enough to help you help me, but maybe it'll spur a thought.