IE7 not digesting JSON: "parse error" - ajax

Question

While trying to GET a JSON, my callback function is NOT firing.
$.ajax({
type:"GET",
dataType:'json',
url: myLocalURL,
data: myData,
success: function(returned_data) {
alert('success');
}
});
The strangest part of this is that:
my JSON(s) validates on JSONlint
this ONLY fails on IE7...it works in Safari, Chrome, and all versions of Firefox, (and even in IE8). If I use 'error', then it reports "parseError"...even though it validates!
Is there anything that I'm missing? Does IE7 not process certain characters, data structures (my data doesn't have anything non-alphanumeric, but it DOES have nested JSONs)? I have used tons of other AJAX calls that all work (even in IE7), but with the exception of THIS call.
An example data return here is: (this is a structurally-complete example, meaning it is only missing a few second-tier fields, but follows this exact hierarchy)
{"question":{
"question_id":"19",
"question_text":"testing",
"other_crap":"none"
},
"timestamp":{
"response":"answer",
"response_text":"the text here"
}
}
I am completely at a loss. Hopefully someone has some insight into what's going on...thank you!
EDIT
Here's a copy of the SIMPLEST case of dummy data that I'm using...it still doesn't work in IE7.
{
"question":{
"question_id":"20",
"question_text":"testing :",
"adverse_party":"none",
"juris":"California",
"recipients":"Carl Chan"
}
}
I am starting to doubt that it is a JSON issue...but I have NO idea what else it could be. Here are some other resources that I've found that could be the cause, but they don't seem to work either:
http://firelitdesign.blogspot.com/2009/07/jquerys-getjson.html (Django uses Unicode by default, so I don't think this is causing it)
Anybody have any other ideas?

Answer 1

The example data you present looks all right but my strong suspicion still is that there is an unclosed comma somewhere like this:
"timestamp":{
"response":"answer",
"response_text":"the text here"
}, <------------
}
IE is the only browser that (correctly) trips over this.
If this is not it, can you show a full data sample (or confirm that the example you show is indeed a full sample)?

Answer 2

Did you already exclude the possibility of a caching issue?
e.g. you tested with IE7 when myLocalURL returned invalid json. IE7 still caches that response and thus it doesn't work. Try adding something like this (e.g. if php) to myLocalURL or make myLocalURL look like myLocalURL?random=123 just for testing to make sure it isn't a caching thing
header("Cache-Control: no-cache, must-revalidate");
header("Expires: 0");
Are you returning a correct content-typ header? e.g.
header("Content-Type: application/json");

Answer 3

I've just encountered exactly the same issue. It turns out that IE7 fails to parse JSON responses that have leading \r\n line feeds in the response body. Your fix of removing {% load customfilter %} works because you removed the new line that was being included after this tag.
An alternative fix would be to just remove the new line to get
{% load customfilter %}{ "question":{ "question_id":"{{question.id}}",
"question_text":"{{question.question_text|customfilterhere}}"
}
}