Hi AndrewB, Thanks for the reply - yes all other aspects of EV client function OK without an authentication prompt. Searching the archive, accessing archived emails, manually archiving an email. Connecting directly to the EV URL using IE also doesn't prompt for dcredentials - the URL has been added to Group policy to specify the zone as Local Intranet.
The same prompting for credentials occurs on machines with IE9 and IE11. The assumption is that the majority of our machines will have this behaviour and the 1 good machine is an exception.
The EV log (set to maximum logging) shows the same 401 error then:
11/07/2014 15:13:03.193[4300][L]: CInternetSendDataBase::DisplayLoginDialog
which I imagine is a failback mechanism when the authentication session cookie is not set.
=============================================
11/07/2014 15:13:03.114[4300][L]: ~CInternetSendDataBase::AddFieldsAndFiles: 0x0
11/07/2014 15:13:03.183[4300][L]: CInternetSendDataBase::ReadResponse: 0x0
11/07/2014 15:13:03.183[4300][L]: CInternetSendDataBase::ReadStatusCode: 0x0
11/07/2014 15:13:03.183[4300][M]: HttpQueryInfo text is 'Unauthorized' status code is '401'
11/07/2014 15:13:03.184[4300][L]: ~CInternetSendDataBase::ReadStatusCode: 0x0
11/07/2014 15:13:03.184[4300][L]: CInternetSendDataBase::ReadResponseHeaders
11/07/2014 15:13:03.184[4300][L]: Received HTTP/1.1 401 Unauthorized
Cache-Control: private
Content-Type: text/html
Server: Microsoft-IIS/8.0
X-AspNet-Version: 2.0.50727
WWW-Authenticate: Negotiate
WWW-Authenticate: NTLM
WWW-Authenticate: Basic realm="Enterprise Vault"
X-Powered-By: ASP.NET
Date: Fri, 11 Jul 2014 15:13:02 GMT
Content-Length: 1293
11/07/2014 15:13:03.186[4300][L]: ~CInternetSendDataBase::ReadResponseHeaders
11/07/2014 15:13:03.186[4300][L]: CInternetSendDataBase::ReadResponseBody
11/07/2014 15:13:03.186[4300][M]: Body is <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"/>
<title>401 - Unauthorized: Access is denied due to invalid credentials.</title>
<style type="text/css">
<!--
body{margin:0;font-size:.7em;font-family:Verdana, Arial, Helvetica, sans-serif;background:#EEEEEE;}
fieldset{padding:0 15px 10px 15px;}
h1{font-size:2.4em;margin:0;color:#FFF;}
h2{font-size:1.7em;margin:0;color:#CC0000;}
h3{font-size:1.2em;margin:10px 0 0 0;color:#000000;}
#header{width:96%;margin:0 0 0 0;padding:6px 2% 6px 2%;font-family:"treb
11/07/2014 15:13:03.189[4300][M]: Body is uchet MS", Verdana, sans-serif;color:#FFF;
background-color:#555555;}
#content{margin:0 0 0 2%;position:relative;}
.content-container{background:#FFF;width:96%;margin-top:8px;padding:10px;position:relative;}
-->
</style>
</head>
<body>
<div id="header"><h1>Server Error</h1></div>
<div id="content">
<div class="content-container"><fieldset>
<h2>401 - Unauthorized: Access is denied due to invalid credentials.</h2>
<h3>You do not have permission to view this directory or page using the credentials that you supplied.</h3>
</fieldset></div>
</div>
</body>
</html>
11/07/2014 15:13:03.192[4300][L]: ~CInternetSendDataBase::ReadResponseBody
11/07/2014 15:13:03.192[4300][L]: StatusCode = 401
11/07/2014 15:13:03.193[4300][L]: CInternetSendDataBase::DisplayLoginDialog
11/07/2014 15:13:03.193[4300][L]: DesktopCommonUtil::GetOutlookWindowHandle: 0x0
11/07/2014 15:13:03.193[4300][L]: CComAutoUnlock<class ATL::CComAutoCriticalSection>::CComAutoUnlock
11/07/2014 15:13:03.194[4300][L]: ~CComAutoUnlock<class ATL::CComAutoCriticalSection>::CComAutoUnlock
11/07/2014 15:13:03.194[4300][L]: CComAutoLock<class ATL::CComAutoCriticalSection>::CComAutoLock
11/07/2014 15:13:03.194[4300][M]: Acquiring lock: 0x6B2F7ADC
11/07/2014 15:13:03.195[4300][M]: Acquired lock: 0x6B2F7ADC