Starting over sounds like the only option to me.
Have you tried a normal or patched form of regular StarEdit yet?
Nah. That won't work. The file is corrupted, something was saved wrong. Starforge is the only way to put player 13, so you need it. However, make sure you ALWAYS backup your map before doing so.
Stop using Starforge to place units, you SCMDraft 1.0 Beta, it works fine!