It is me again with another problem.
I managed to start Design Studio normally, and as I was in the process of creating a new application, I had to declare a new Data Source.
I had a unx created for that purpose as well as a connection. As I picked the unx as data source, I had to declare also a query, and when I did that, i.e. I clicked on Refresh on Edit Query Specification screen, I got an error message [Microsoft][ODBC Driver Manager] The specified DSN contains an architecture mismatch between the Driver and Application.
The unx is based on a SQL Server database for which I created a DSN with odbcad32. I tested the connection to the DB and it worked.
Therefore I have no idea as why this error message is occuring.
Thank you for your help.