A recent client had this error on their MS SQL Server out of the blue. After much investigation and trial/error to correct. The following solution saved the day:
- Login as “Administrator”.
- Go to “Start > Programs > Microsoft SQL Server 2005 > Configuration Tools > SQL Server Configuration Manager”
- Click “SQL Server 2005 Network Configuration > Protocols for MSSQLSERVER”
- Double click “TCP/IP” in the right side.
- Change “Listen All” to “Yes” in the popup window.
- Click “Ok” button
- Start your MSSQLSERVER service
Much thanks to the following article: