SDM downloads catalog and updates to itself using the FTP protocol by default and HTTP optionally. For more information, please login to this forum and read the forum posts with the word FAQ in them.
If SDM is displaying an warning or error such as "Unable to download Product Catalog", please disregard it, exit SDM and re-launch it. The warning/error should not show up. If you are having some other problem, please submit an SDM log by selecting Help from the main menu and then selecting "Provide Feedback to HP".
The first thing that SDM is make sure it is running the latest version, so installing an earlier version will not serve any purpose. Please launch SDM duplicate the steps that are producing a problem and send an email to the SDM Support Team from the SDM main menu (Help - Provide Feedback to HP) from that failing SDM session.