I have a had a couple of instances that jQuery.Multiselect will not render correctly in IE9? It could my my own installation but this is what is getting rendered (Chrome and Mozilla work fine):
Demo page and docs links:
http://labs.abeautifulsite.net/projects/js/jquery/multiSelect/demo/
http://abeautifulsite.net/blog/2008/04/jquery-multiselect/
Related Case:
Multiselect list will not drop down in IE9?
IE9:
Just to be clear, THE ASK is a work around using the same control

Chrome:

The problem is with the bgiframe plugin, as Brandon stated. I have updated the dependency, reorganized the image files into a folder, and pushed a new version (1.2.3). I recommend downloading it from the project page: http://abeautifulsite.net/blog/2008/04/jquery-multiselect/
Alternatively, here is the direct link to the ZIP: http://labs.abeautifulsite.net/projects/js/jquery/multiSelect/jquery.multiSelect-1.2.3.zip