The cultist bug is not the only one, and some compatibility issues were added between patch 1.1 and 1.2.
BCGaius: There were issues when Chaos Terminators and certain daemon summons started showing up that would invariably crash the game, and I could never find a satisfactory workaround.
IIRC there was something about it and patch 1.2 - I don't remember exactly if it was supposed to fix that, or it caused it.
Edward_Carnby: If you have original CD - I can tell you how to run game on modern PC without crash on chaos cultist turn .
There is one catch-all solution, but it also requires you to own a Windows 98 setup disc.
Set up a virtual machine - such as Microsoft Virtual PC, or VMWare. Install Windows 98 in it. Install Chaos Gate in it. Done.
wassermann: I have another win xp machine, works flawlessly on that. But the original game did as well.
You're lucky, then. The game has been known to have crippling issues from Windows 2000 onwards.