Prompted for credentials for proxy server office14client.microsoft.com when launching an Office 2010 application Content provided by Microsoft Applies to: Microsoft Office 2010 Service Pack 2Excel 2010Microsoft Word 2010PowerPoint 2010Microsoft Outlook 2010Microsoft OneNote 2010Access 2010 More Select Product Version All Products Symptoms When you launch an Office 2010 application (such as Excel 2010 or Word 2010), you may be prompted for credentials for a proxy server - office14client.microsoft.com - as shown in this image:The prompt may repeat after being dismissed. Cause This is a known issue with the update described in Knowledge Base article 2956191 . Resolution To resolve this issue, please install the update found here: http://www.microsoft.com/en-us/search/result.aspx?q=KB3054875&form=DLC Last Updated: May 28, 2015 Did this solve your problem? Yes No Tell us what we can do to improve the article Submit Thanks! Your feedback will help us improve the support experience.