DataSource Controls :: 2147467259/A Network-related Or Instance-specific Error Occurred While Establishing A Connection To SQL Server

I am using Asp.Net MVC 2.0 for creating a user and assigning properties to the user at the same time. I am using my Windows account to access database on my local computer. I am using pre-installed MVC code o create a user with unique user name and password. User is created OK. Then I want to add profile properties like First and Last name at the same time.

I am creatingProfileBase object:

ProfileBase profileBase = ProfileBase.Create(profileInformation.UserName);

where profileInformation is a RegisterModel and has user info.

When I am trying to:

profileBase.SetPropertyValue(.....);

I am getting the following error # 2147467259 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: Shared Memory Provider, error: 40 - Could not open a connection to SQL Server)"}

Why is my connection string works fine the first time and not working now? And how to configure connection to use TCP-IP?

I have SQL Server Browser running ander Local account and openned port in my Firewall.