After upgrade from 2005 to 2007, some workstations get this error:
Microsoft SQL Server Login
Connection failed
SQLState; u201808001'
SQL Server Error: -1
[Microsoft] [SQL NATIVE CLIENT] SQL Network Interfaces: error locating server/instance specified [xFFFFFFFF]
Connection failed;
SQLState: 'HYT00'
SQL Server Error: 0
[Microsoft] [SQL NATIVE CLIENT]Login timeout Expired
Connection failed;
SQLState: '08001'
SQL Server Error: -1
[Microsoft] [SQL NATIVE CLIENT] an Error has occurred while establishing a connection the sql server. when connecting to sql server 2005, this failure may be caused by the fact that under the default settings sql server does not allow remote connections