If you are using Windows XP, please note that Windows XP does not support IE9.
To troubleshoot the installation issue, please refer to:
Failed install of IE8 - setup cannot continue because a more recent version...
http://answers.microsoft.com/en-us/ie/forum/ie8-windows_other/failed-install-of-ie8-setup-cannot-continue/9a113e20-c3b5-4877-aa4a-352f524a60de
IE 9 install msg: "Setup can't continue because a more recent version of Internet Explorer is installed on your computer"
http://answers.microsoft.com/en-us/ie/forum/ie9-windows_7/ie-9-install-msg-setup-cant-continue-because-a/37f319f0-325f-46c7-824c-252265e65bd0
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