I have IIS 6.1 on Windows Server 2008 SP1. There is one web application which has only Windows Authentication enabled. This has just one provider: NTLM.
When I works, it works fine - until the server is rebooted. Following a reboot, the login dialog is always displayed but logins always fail.
I have tried restarting both IIS and the application pool but this does not help. What does work is enabling and disabling Authentication mechanisms - e.g. Anonymous. After fiddling around for a while, NTLM works - until the next server start.
In the log I can see the following:
#Fields: date time s-ip cs-method cs-uri-stem cs-uri-query s-port cs-username c-ip cs(User-Agent) sc-status sc-substatus sc-win32-status time-taken
2016-01-14 12:56:11 127.0.0.1 GET /Pages/MainPage.aspx - 80 - 127.0.0.1 Mozilla/5.0+(compatible;+MSIE+10.0;+Windows+NT+6.1;+WOW64;+Trident/6.0) 401 2 5 0
2016-01-14 12:56:11 127.0.0.1 GET /Pages/MainPage.aspx - 80 - 127.0.0.1 Mozilla/5.0+(compatible;+MSIE+10.0;+Windows+NT+6.1;+WOW64;+Trident/6.0) 401 1 2148074254 0
What could be causing this? What is the solution?