I hate developing in IE because it provides the most absolutely completely useless error message for JavaScript. I just had to get that out there.
Ok, the error was really ocurring in the Adobe SVG plug-in inside IE, but I think it uses the same or a similar JS engine. At any rate the errors reported are the same as the kind you'd get from IE.
I was able to discover the location of the error, but not the cause. At least, not from the vague error message I received. The specific error message I would encountering was "Expected identifier, string or number" ... with line/column information that was pretty much useless. Luckily I found a blog post that mirrored my situation exactly.
The error was in the JSON returned in response to an XMLHTTPRequest. Apprently the trouble was caused by an extra comma I had forgotten to take out. Seems like something that should cause problems in any JS engine due to bad syntax, but then again I do need to do more research on object notation before I can say something like that with certainty.
References: