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.
When you try to connect to the sql server 2005 remotely the above error may occur. One reason for this eroor is your sql server 2005 configuration is not accepting remote connection. By default sql server express edition and sql server 2005 developer edition do not allow remote connections. To configure sql server 2005 to allow remote connections, complete the following steps.
1. Eanble remote connections on the instance of sql server.
2. Turn on the sql server browser service.
3. Do firewall configuration to allow network trafic related to sql server and browser service.