I've just started playing the game with the Heretek expansion enabled. The game randomly goes to black screen, no cursor visible, with a loud buzzing sound. After a while it displays a Windows message saying tha it encountered a problem and is restarting. This happens randomly: during missions / dialogues / cohort screen, it doesn't seem related to anything happening in particular.
I ran the integrity check with Galaxy and restarted the game, it still happens.

Suggestions? Thanks.