SQL problem!

hi there

my SQL Authentication used to work fine but for some reason it doesnt now. I have not changed the password or anything at all. I have even uninstalled SQL and re-installed it but still get the same error. What can it be?

System.Data.SqlClient.SqlException: Login failed for user 'NT AUTHORITY\NETWORK SERVICE'. at System.Data.SqlClient.ConnectionPool.CreateConnection() at System.Data.SqlClient.ConnectionPool.UserCreateRequest() at System.Data.SqlClient.ConnectionPool.GetConnection(Boolean& isInTransaction) at System.Data.SqlClient.SqlConnectionPoolManager.GetPooledConnection(SqlConnectionString options, Boolean& isInTransaction) at System.Data.SqlClient.SqlConnection.Open() at LeeAult.WebForm1.DoLogin() in c:\inetpub\wwwroot\leeault\admincplogin.aspx.cs:line 93


???

Changed anything in IIS? Could be caused by allowing anonymous access. Also may happen if the network service hasn't been granted access to the database in SQL