I've just solved my own problem 20-seconds before posting the question!    So thought I'd post the solution here:

 

PROBLEM:  Connecting to an MS SQL Server database via Database Expert (using either an "ODBC (RDO)" or "OLE DB (ADO)" connection) shows no available databases in the dropdown (even when creating the same ODBC connection via "Administrative Tools -> Data Sources" is successful);

 

SOLUTION:  Update CR2011 with "Support Package 1":

(http://service.sap.com/sap/bc/bsp/spn/bobj_download/main.htm);

 

Hope this helps someone - I was pulling my hair out!

 

Possible cause is installing MS SQL Server 2012 on your local machine... this updated my Native SQL Driver to "11.0" - and then trying any other Native Drivers (ie: "10.0" and previous) wouldn't work.

 

Cheers,

 

Steve.