Sorry for my poorly written reply up there; I never type nor speak very coherently after having been up for nineteen hours strait, but I'm okay.
I've got a new theory on it now. I know that in the Bastion escort mission there are three fighter killers providing additional fire support. I also know that in the next mission, the last one of the game, all three are supposed to be there with the "Red Alert Status" box checked in the Misc. Options. I also know that two of the three fighter killer cruisers (aka GTC Aeolus...sorry) are set to be Destroyed 0 seconds before the mission. Alpha, Beta, and Gamma wings are all set for Red Alert Status as well, meaning they carry over from one mission to the next with their current hull integrity/ammunition statistics. So it's possible that if the ships.tbl file got messed around with in such a way that a Colossus replaced the Aeolus or one of the fighters in Alpha, Beta, or Gamma (the mission file itself would have to be messed up in this case) it could cause the big ship to explode as it did. It's just a ragged theory I put together at 1213 in the morning, so now it's everybody's turn to poke lots of holes in it.
I think the mission where the Colossus is destroyed is spent near the Capella/Gamma D. jump node, whereas the last mission takes place in the space surrounding the Capella/Vega jump node, so I believe they're two different places. My facts and trivia on this matter are quite rusty, so I dunno how accurate all the above is. Anyways, for the whole Red Alert/Destroyed Before Mission thing, I think ships that are destroyed before the mission begins never exhibit the exploding shockwave effect, and in my copy of FS2 the fighters that died in the Bastion escort mission turn up as completely disabled Ulysses in the next mission. Possibly a bug.
[This message has been edited by Slasher (edited 08-28-2001).]