http://developers.de/blogs/damir_dobric/archive/2009/08/28/authentication-problems-by-using-of-ntlm.aspxWhen configuring NTLM in an enterprise you may get error message like this one: ” Authentication error HTTP 401” (sometimes 401.1). Depending on the client you use this error can be shown for example in the browser if you try to access some page on someenCommunityServer 2008 SP1 (Build: 30619.63)http://developers.de/blogs/damir_dobric/archive/2009/08/28/authentication-problems-by-using-of-ntlm.aspx#191893Fri, 27 May 2011 02:27:13 GMT7e491611-45ad-4dae-a68f-c4cb64439510:191893Dharma<p>Thank you so much..my code worked fine in UAT but when we move it to Prod we got this issue.. your blog helped me to resolve it quickly.</p> <div style="clear:both;"></div><img src="http://developers.de/aggbug.aspx?PostID=191893" width="1" height="1">http://developers.de/blogs/damir_dobric/archive/2009/08/28/authentication-problems-by-using-of-ntlm.aspx#9142Mon, 07 Sep 2009 09:49:24 GMT7e491611-45ad-4dae-a68f-c4cb64439510:9142Sascha<p>Don&#39;t forget to create the DisableLoopbackCheck Key (DWORD)!</p> <div style="clear:both;"></div><img src="http://developers.de/aggbug.aspx?PostID=9142" width="1" height="1">http://developers.de/blogs/damir_dobric/archive/2009/08/28/authentication-problems-by-using-of-ntlm.aspx#9143Tue, 01 Sep 2009 20:47:15 GMT7e491611-45ad-4dae-a68f-c4cb64439510:9143Flowman<p>Thanks, for the post. We spent almost two days to figure out why we got these 401.1 errors, and now it works like a charm. Thanks again.</p> <p>Otto Horvath</p> <p>MS MVP - Group Policy</p> <div style="clear:both;"></div><img src="http://developers.de/aggbug.aspx?PostID=9143" width="1" height="1">