This issue is a JSON issue.
We had lots of JSON objects in the page and things were all working fine on Firefox and IE9 until we started testing JSON objects on IE7 and we kept having the following error “JSON undefined”
After some research, I found that there’s no native support for JSON in IE7, for this reason, one should use json2.js created by Douglas
Off course another main point that’s worth noting in constructing your JSON objects would be, getting rid of all the trailing commas that are extra at the end of JSON last element in the array. This does matter in IE but doesn’t in other browsers.