An error has occurred while establishing a connection to the server

Details
Product:	SQL Server
ID:	-1
Source:	MSSQLServer
Version:	10.0
Component:	SQLEngine
Message:	An error has occurred while establishing a connection to the server. When connecting to SQL Server, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 28 - Server doesn't support requested protocol) (Microsoft SQL Server, Error: -1)
Explanation
The SQL Server client cannot connect to the server. This error could be caused by one of the following reasons: A specified SQL Server instance name is not valid. The TCP, or named pipes protocols are not enabled. The firewall on the server has refused the connection. The SQL Server Browser service (sqlbrowser) is not started.
User Action
To resolve this error, try one of the following actions: Check the spelling of the SQL Server instance name that is specified in the connection string. Use the SQL Server Surface Area Configuration tool to enable SQL Server to accept remote connections over the TCP or named pipes protocols. For more information about the SQL Server Surface Area Configuration Tool, see Surface Area Configuration for Services and Connections. Make sure that you have configured the firewall on the server instance of SQL Server to open ports for SQL Server and the SQL Server Browser port (UDP 1434). Make sure that the SQL Server Browser service is started on the server.
Version:	9.0
Component:	SQLEngine
Message:	An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 28 - Server doesn't support requested protocol) (Microsoft SQL Server, Error: -1)
Explanation
The SQL Server client cannot connect to the server. This error could be caused by one of the following reasons: The firewall on the server has refused the connection. A specified SQL Server instance name is not valid. The SQL Server Browser service (sqlbrowser) is not started.
User Action
To resolve this error, try one of the following actions: Make sure that you have configured the firewall on the server instance of SQL Server to open the SQL Server Browser port. Make sure that the SQL Server Browser service is started on the server. Check the spelling of the SQL Server instance name that is specified in the connection string. Use the SQL Server Surface Area Configuration tool to enable SQL Server to accept remote connections. For more information about the SQL Server Surface Area Configuration Tool, see Surface Area Configuration for Services and Connections.