This error resembles the one discussed at #39
Links with a 'rel' attribute like "rel='address:test'" will be found and prepared by jQuery Address' function $.fn.address. One of the things it does is add the 'submit' event through the $.fn.live function. jQuery actually adds a 'click.specialSubmit' event (on line 3237 of v1.6.2), a function that checks the 'type' attribute of the clicked element.
If the link contains a (Cufon) VML object and this object is clicked, jQuery's 'click.specialSubmit' function is invoked on this object, this function checks the 'type' attribute and makes Internet Explorer 7 en 8 alert an error.
Example of VML object type error in MSIE7/8
Example of VML object with 'submit' event bound by jQuery
Example of Basic jQuery, jQuery Address and Cufon setup
Extensively discussed at: http://www.sitecrafting.com/blog/jquery-cufon-dont-mix/
Reported to Sizzle: jquery/sizzle#17
Reported to jQuery: http://bugs.jquery.com/ticket/9807