My web service app on my Windows XP box is trying to log in to my sql server 2005 database on the same box. The machine is part of a domain. I am logged in in the domain and I am an admin on my machine. I am using Windows Authentication in my connection string as in "Server=myServerAddress;Database=myDataBase;Trusted\_Connection=True". SQLServer is configured for both types of authentication (mixed mode) and accepts remote connections and accepts tcp and named pipes protocols. Integrated authentication is enabled in IIS and with and without anonymous access. 'Everyone' has access to computer from network setting in local security settings. ASPNET is a user in the sql server and has access to the daatabase. user is mapped to the login.

The app works fine for other developers which means the app shouldn't be changed (It's not new code). So it seems it's my machine which has an issue. 

I am getting the error "Login failed for user ''. The user is not associated with a trusted SQL Server connection" Note the blank user name. Why am I getting this error when both the app and database are on my machine? I can use SQL Server authentication but don't want to. I can connect to the database using SSMS and my Windows credentials.

It might be related to setspn, kerberos, delegation, AD. I am not sure what further checks to make?