Symptoms
When you try to install Microsoft SQL Server 2008, the installation process mayfail. Additionally, the following error may be written to the setup log:

DateTime Slp: Configuration action failed for feature SQL_Engine_Core_Inst during timing ConfigRC and scenario ConfigRC.
DateTime Slp Slp: Microsoft.SqlServer.Configuration.Sco.ScoException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 – No connection could be made because the target machine actively refused it.)
System.Data.SqlClient.SqlException: An error has occurred while establishing a connection to the server.When connecting to SQL Server Version,, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: TCP Provider, error: 0 – No connection could be made because the target machine actively refused it.)This problem occurs if you have defined a server alias in the Client Network Utility for a protocol other than Shared Memory.
Resolution
This problem occurs because the user-defined server alias does not allow for shared memory connections.