Im sure most of us who have played the 1.9 story missions have had game crashes after killing the strike carrier...
There are solutions to get past this problem, but I will tell you the easiest way.
After you are briefed by Orillion telling you that 2 squads of ships will come- the first sqaud taking care of the fighters and the second squad killing the carrier, Immediately make a save manually.
This was my save:
After you have done that, restart the game and load your save, not the autosave. It whould work then without a crash. Well, if it does crash just load the save again... It is sure to work fine.
Good luck.