I'm trying to produce a mission in which a GTBS Archangel jumps in and destroys two corvettes without taking damage. So I make it invulnerable to accomplish this. However, when I save, the damned program turns off the invulnerability! It was working just five minutes before... and furthermore it kept coming up with an error in the mission that FRED couldn't detect: it looks for a nonexistent tag called [$IFF] in the mission file. I think when it finds that error, it disallows the ship to be invulneralbe. A large amount of the plotline hinges on this ship being invulneralbe (until I say otherwise), so why why WHY is FRED suddenly so uncooperative? If it matters, I'm running both FRED and Freespace Open on the latest CVS build.