Since Internet Explorer 9 was released, I received some negative feedback on one of my sites using with it.
I looked through the forums for help, and found only information on broken IE9 javascript in official beta version. I installed official update and it turned out to be that my problem is not going away on the latest version. Clicking on “Compatibility view” button resolved the issue. So, the problem was only in getting proper compatibility mode for every person. Happily, Microsoft still trying to be compatible with older sites.
Quick search in Google returned this blog post “IE9, compatibility mode and the META tag“.
Adding the following tag just after HEAD tag, eliminated my problem.
Note: seems that all sites, where jQuery is used, need to get this tag for compatibility with IE9