Hello, I have installed SQL Server 2008 Developer on Windows 7 64 bit. In Management Studio I cannot register the default instance MSSQLSERVER, it cannot find it although the service is running. I get the message:

Cannot connect to PHOENIX\MSSQLSERVER.

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: SQL Network Interfaces, error: 25 - Connection string is not valid) (Microsoft SQL Server, Error: 87)

However Management Studio does show the SQL Server 2005 Express instance (that was installed with VS 2008 Pro) which appeared as already registered. I an using Windows Authentication as I installed it in mixed mode. Any ideas would be appreciated, many thanks

paul