Do you use console.log() to debug your JavaScript? Well, I've got news for you.. console.log() breaks Internet Explorer; even if all instances of it are commented out! A quick check you can do to see if console.log() is indeed the source of your problem, is to open the console in Internet Explorer and see if the problem goes away. The reason for this is that console.log() does not exist in Internet Explorer unless the developer tools are active. So, for regular IE users,console.log() is a show stopper.
The Solution
You can either make sure you don't ship your JavaScript with any instances of console.log() in it, or you can place the following code near the top of your JavaScript to ensure that it exists (albeit non-functional):
if ( ! window.console ) console = { log: function(){} };