Getting intermittent connection error: "A network-related or instance-specific error occurred..." (4280007)

Getting the following error intermittently when connecting with Toad. Unable to connect to the db server.

"A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)"

The issue is not on the Toad end but on the SQL Server end but the following suggestion might help.

1. Go to the Server where you SQL Server Database is located at

2. Go to Start | Run and type in “REGEDIT”

3. Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL.<InstanceNumber>\MSSQLServer\
SuperSocketNetLib\TCP\

Where MSSQL.<InstanceNumber> is the instance you are trying to connect to

4. From the TcpPort on the right hand side grab the port number, whatever it shows.

5. Once you have the port number go back to Toad and make your connection like this.

<server>\<SQL Server DB>,<Port Number>

e.g. toadXP\TSQLServer2005,2304
 

See screen shot SOL85659_Fig_1.jpg