Are you using a data store, e.g., ItemFileReadStore?

If so, can you post here the data that the server (or page) provides the data store?

You may want to create a very small test version of your web page, with just enough content/widgets to demonstrate the problem, and then post it in a reply, here, putting the full html page contents between code tags,

Then others can review it and find a solution. Thanks.

The reason I asked about a store is that Firefox tolerates/permits a JSON array with a trailing comma, e.g.,

var data = {identifier:'name', items:[{name:'bob'},{name:'sally'},]};

whereas, IE gives a similar error to the one that you see.

Ensure that your data does not include the trailing comma (after the last "item" in the array), i.e., should be like this (not with comma as above):

var data = {identifier:'name', items:[{name:'bob'},{name:'sally'}]};