I just installed on my system Internet Explorer 9 "final version" and I have the same display problem
I note that the title for the module s5_horizontal_accordion s5_ha slide does not display correctly.
See homepage with IE9 here : http://www.acupuncture-traditionnelle.com
We also found this problem on Tab 1 text Fixed theme for eshopper jooomla 1.6.1 (Link Twitter)
While with Internet Explorer 8 and Firefox 3.6.15 it displayed without problems
I am looking for a solution