On my Windows 7 x64 PC with Visual Studio 2010 Premium and SQL Server 2008 R2, for my C# ASP.NET class, I am developing an app that uses the Login and CreateUserWizard controls. After creating a few users in the ASP.NET Configuration tool, when I run the app in Debug Mode in VS 2010, I can log in and create a new user with no problem.

When I run the app via IIS (localhost/ Ch19Authenticate), I can access the non-secured screens with no problem. When i try to log in, I ger an error:

Server Error in '/Ch19Authenticate' Application.

Failed to generate a user instance of SQL Server due to a failure in impersonating the client. The connection will be closed.

Description:An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Data.SqlClient.SqlException: Failed to generate a user instance of SQL Server due to a failure in impersonating the client. The connection will be closed.

Source Error:

An unhandled exception was generated during the execution of the current
 web request. Information regarding the origin and location of the
exception can be identified using the exception stack trace below.

Stack Trace:

[SqlException (0x80131904): Failed to generate a user instance of SQL Server due to a failure in impersonating the client. The connection will be closed.]
   System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +5064458
   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() +234
   System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +2275
   System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK) +35
   System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, SqlConnection owningObject) +183
   System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, TimeoutTimer timeout) +239
   System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, TimeoutTimer timeout, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +195
   System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +232
   System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +5078107
   System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +33
   System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +524
   System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66
   System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +479
   System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +108
   System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +126
   System.Data.SqlClient.SqlConnection.Open() +125
   System.Web.DataAccess.SqlConnectionHolder.Open(HttpContext context, Boolean revertImpersonate) +95
   System.Web.DataAccess.SqlConnectionHelper.GetConnection(String connectionString, Boolean revertImpersonation) +206
   System.Web.Security.SqlMembershipProvider.GetPasswordWithFormat(String username, Boolean updateLastLoginActivityDate, Int32& status, String& password, Int32& passwordFormat, String& passwordSalt, Int32& failedPasswordAttemptCount, Int32& failedPasswordAnswerAttemptCount, Boolean& isApproved, DateTime& lastLoginDate, DateTime& lastActivityDate) +827
   System.Web.Security.SqlMembershipProvider.CheckPassword(String username, String password, Boolean updateLastLoginActivityDate, Boolean failIfNotApproved, String& salt, Int32& passwordFormat) +105
   System.Web.Security.SqlMembershipProvider.ValidateUser(String username, String password) +106
   System.Web.UI.WebControls.Login.AuthenticateUsingMembershipProvider(AuthenticateEventArgs e) +60
   System.Web.UI.WebControls.Login.OnAuthenticate(AuthenticateEventArgs e) +129
   System.Web.UI.WebControls.Login.AttemptLogin() +127
   System.Web.UI.WebControls.Login.OnBubbleEvent(Object source, EventArgs e) +101
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) +125
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +167
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

My settings in IIS for the app are

.NET Authorization Rules - Allow All Users

.NET Trust Levels - Full

Connection Strings - LocalSqlServer - Custom - data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true

Anonymouus Authentication - Enabled

Authorization Rules - Allow All Users

Application Pool - ASP.NET v4.0

I have seen similar posts in the IIS and SQL Server forums, but they refer to user profile problems, the IIS version is older, it's a different OS. SQL Server is older or a different version, or it's an older version of ASP.NET..

What is different/missing in my IIS settings such that I can log in and create users while running in debug mode, but not when running under IIS?

Thanks.