By default, SQL Server 2005 Express Edition is installed only one connection protocol enabled:

* Shared Memory - SQL Server connection protocol for applications that are running on the same machine where the SQL Server is running. For example, if you are running SQLCMD tool on the SQL Server machine, it will use the "Shared Memory" protocol.

If you want application that are running remotely to connect and access the SQL Server you need enable the "TCP/IP" protocol.

For applications that are running on the same machine as the SQL Server, but they do not support "Shared Memory" protocol, you also need to enable the "TCP/IP" protocol for those applications. ODBC Manager is an application that requires the "TCP/IP" protocol to connect to the SQL Server.

In order for the SQL Server to accept network connections, you also need to run SQL Server Browser Service on the SQL Server machine.

In summary, there are two requirements for a SQL Server to accept network connections:

* Start SQL Server Browser Service on the SQL Server machine.

* Enable the TCP/IP protocol support on the SQL Server.