SQL Authentication login error

I was trying to connect to Sql Server Management Studio today using SQL Server Authentication and received a Microsoft SQL Server, Error: 18452. "The user is not associated with a trusted SQL Server connection."

PROBLEM: Cannot login with any account using SQL Server Authication because the Server Authentication mode does not allow it. (We need to change it so SQL Server Authentication is allowed).

SOLUTION:
Step 1.) Log into Management Studio using Windows Authentication
Step 2.) Right Click on the Server and select Properties
Step 3.) Select the Security page from the left side navigation.
Step 4.) Select SQL Server and Windows Authentication mode.
Step 5.) Press OK
Step 6.) Right click on the Server and select Restart

You should now be able to login with the account that requires SQL Server authentication.

Hope this helps.

Reference:
http://chkiran.wordpress.com/2008/06/20/sql-server-authentication-not-working/