*** SOLUTION TO THE CULTIST BUG ***
After examining the WeapDef.dat file under the Data folder I've found out how to solve the infamous cultist bug.
YOU NEED TO START A NEW GAME FOR THE CHANGES TO TAKE EFFECT
(or it may be enough to save again, but I haven't tested)
1. Open WeapDef.dat in the Data folder under the Chaos Gate folder.
2. Find the section containing the Laspistol.
3. Change "PlazPistHit.wav" to "PlazpistHit.wav" (note the lower case 'p').
4. Save.
5. Start a new game.
Enjoy your cultists without CTD.
