SQL Server 2005 cannot connect to 127.0.0.1

"Problem description" If you connect to the local database server, the server name can be filled in: 127.0.0.1 or localhost or native machine full name (such as home), sometimes with a native machine name can log on to SQL Server 2005, but cannot connect with 127.0.0.1 or localhost.

The "solution" may be that the remote connection protocol is not open.
Open the surface area configuration for services and connections, SQL Server perimeter configuration,->database engine-> remote connection, select Local connection and remote connection, select both TCP/IP and named pipes, Click the "Apply" button;

Back to the Database engine-> service, click the "Stop" button, after the service stops, click on the "Start" button to restart the databases service.

SQL Server 2005 cannot connect to 127.0.0.1