Yeah, the galaxy forge you are using is for the current version of Sins of a Solar Empire. As you're using an out of date version, you can (in order of easiest to hardest if possible) A. Update you game B. See if Harpo's map updater will go back to 1.05 C. Ask someone to upload the old galaxy forge (I'd try the 7 deadly sins mod page if they are still using 1.05). Another option might be to see what has changed since 1.05 (sometimes its only the version number at the top) and change your map manually in notepad.
Edit: Also, searching for galaxy forge sins 1.05 on google showed some promising links on other sities you may want to try if updating your game is not an option.
