I'm working on a C# WinForms application for a client. They are using SQL 2005.

When I remote in I can open SQL Management Studio and work normally.

When I try to run my application, I get:

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: 26 - Error Locating 
Server/Instance Specified)

The instance name appears to be MSSQLSERVER. How do I veryify this?

So I'm not even sure what this is saying. I spent some time on the phone with the network manager, and we believe SQL to be configured correctly. Remote connections are set up, and I appear to have all rights.

The last time I saw this, a few months ago, I followed the directions here
http://www.mydigitallife.info/2007/10/31/error-has-occurred-while-establishing-a-connection-to-sql-server-2005-which-does-not-allow-local-and-remote-connections/ and it worked fine. This time no luck.

Anyone know what's wrong?