This is a common issue occurring with people who are using versions of Endnote below X4. Endnote X4 is the only version of Endnote compatible with Windows 7 and Microsoft Office 2010. When using a version below X4 in Microsoft Word 2010, the program becomes unresponsive and Not Responding message occurs. In order to prevent Word from becoming unresponsive you will need to disable the Endnote Add-Ins.

In the Start Menu go to All Programs and then Microsoft Office 2010 and then hold the Ctrl button and then click on Microsoft Word 2010. A window will be pop up asking you if you would like to run Microsoft Word in 2010 in Safe Mode. Click Yes.

Once in Microsoft Word 2010, select File and then Options on the left hand panel. Go to Add-Ins and then select COM Add-Ins from drop down menu under Manage and then click Go...