Depending on your version of Internet Explorer (i.e. 11) you may need to perform the following fix.
Add the following script to your master page.
<script language="javascript"> /* IE11 Fix for SP2010 */ if (typeof UserAgentInfo.strBrowser !== 'undefined' && !window.addEventListener) { UserAgentInfo.strBrowser=1; } </script>
Note: And should be added right above the </body> tag on the master page (in your case v4.master).
Please refer to the article http://social.technet.microsoft.com/Forums/sharepoint/en-US/5a81a95b-a4d0-4e6c-a8c4-5602698e5a32/windows-81-and-ie11-critical-error-object-doesnt-support-property-or-method-addeventlistener