You can add a meta tag to the head of the web page that will force IE to render the page in standards view. This is something that can be added to the header.php of the WP theme. There are other suggestions that may also work for you discussed over at stackoverflow:
The support post ‘Upgraded to latest version, Calendar still not viewable IE 8’ is closed to new replies.
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Support forum for Event Espresso 3 and Event Espresso 4.