IE9 - jQuery - "SCRIPT11: The operation attempted to access data outside the valid range"

Question

I'm using a simple jQuery plugin that creates a unique fingerprint for each user so that we can track/recognize users coming from a specific referral URL.

It works fine everywhere EXCEPT Internet Explorer 9 (yes, it works in IE7 & IE8, even though the web page looks goofy).

The error I'm receiving is:

SCRIPT11: The operation attempted to access data outside the valid range

The code is below (error occurs on Line 21, Column 7). I'm about to go through it all and comment out each of the entities to see if it's one of them in particular that's causing this error.

Thanks!

( function($) {

  // Calling `jQuery.fingerprint()` will return an MD5 hash, i.e. said
  // fingerprint.

  $.fingerprint = function() {

    // This function, `_raw()`, uses several browser details which are
    // available to JS here to build a string, namely...
    //
    // * the user agent
    // * screen size
    // * color depth
    // * the timezone offset
    // * sessionStorage support
    // * localStorage support
    // * the list of all installed plugins (we're using their names,
    //    descriptions, mime types and file name extensions here)
    function _raw() {
      // That string is the return value.
      return [
        navigator.userAgent,
        [ screen.height, screen.width, screen.colorDepth ].join("x"),
        ( new Date() ).getTimezoneOffset(),
        !!window.sessionStorage,
        !!window.localStorage,
        $.map( navigator.plugins, function(p) {
          return [
            p.name,
            p.description,
            $.map( p, function(mt) {
              return [ mt.type, mt.suffixes ].join("~");
            }).join(",")
          ].join("::");
        }).join(";")
      ].join("###");
    }

    // `_md5()` computes a MD5 hash using [md5-js](http://github.com/wbond/md5-js/).
    function _md5() {
      if ( typeof window.md5 === "function" ) {
        // The return value is the hashed fingerprint string.
        return md5( _raw() );
      }
      else {
        // If `window.md5()` isn't available, an error is thrown.
        throw "md5 unavailable, please get it from http://github.com/wbond/md5-js/";
      }
    }

    // And, since I'm lazy, calling `$.fingerprint()` will return the hash
    // right away, without the need for any other calls.
    return _md5();
  }

})(jQuery);