Hi Dave
First thing I would check is the Server Name setting in your registry at HKEY_LOCAL_MACHINE\Software\Dorset Software\Recorder 6. What is the value and does it match the name of the instance you created on the machine (SQLEXPRESS is the default name). So for example if your machine is called A and the instance is called B, it should read A\B.

If this looks correct, you could check to see that the SQLExpress instance is actually running. In Control Panel, select Administrative Tools\Services and look through the list for SQL Server (...) where ... is your instance name. It should be started with the startup type set to automatic.

Let us know how you get on,