@RogerCooper I'm assuming you're talking about the Map Creator listed in the Download Maps window. If so, it's probably the same root cause because that file is hosted on SourceForge, as well.
I wonder if the reason you are seeing this problem consistently is because, at some time in the past, you selected a preferred mirror when downloading a file from SourceForge, and that mirror is the one with the bad SSL/TLS certificate. Deleting any SourceForge cookies from your browser may fix that problem for you. As I said in a previous comment, I only see this problem intermittently.
There are alternate locations from which you can download the standalone Map Creator (albeit from outside the game). On GitHub, the latest snapshots of Map Creator are available at
Version 1 Version 2You can also download any previously released version of Map Creator from the Google Code archive:
Version 1 Version 2Note that we've been discussing what the benefits of these standalone tools are compared to the in-game map creation tools (available from Engine Preferences > Run the Map Creator and Engine Preferences > [Beta] Run the Map Creator). Please feel free to contribute to the discussion so we can make a better decision on the future of the map creation tools.