JS error with i18n

I seem to be experiencing this error ... though instead of linktocontent_menu giving a TypeError, they're both announcing the SyntaxError:

After some experimentation I have found that switching off the Internationalization module fixes this ... I suspect it's the part of the module that meddles with URLs (each path is prefixed with a language code - eg http://example.com/node/1 becomes http://example.com/en/node/1 for English or http://example.com/fr/node/1 for French), which could potentially interfere with callbacks...? Omitting the language code generally seems to trigger a redirect to the path for the current or default language, I don't know what impact that would have on a jQuery call.

Anyway, I've got it working for one of my sites (which was only using one language but used to have more, hence i18n being installed) but another of them definitely does use more than one language so any suggestions for getting the two modules to play nicely together would still be helpful.