Usually it's bad cache that causes this. Uninstalling won't remedy it either. Try this: http://www.java.com/en/download/help/plugin_cache.xml
If that doesn't work clear your browser temp files and cookies as well. I just tested this and it works fine with IE 9 and the latest Java 6 update.
If that doesn't work clear your browser temp files and cookies as well. I just tested this and it works fine with IE 9 and the latest Java 6 update.