1. Load the game normally via Steam or a launcher or whatever
2. Go in to the \Configure\Expansions menu and change the mod configuration (doesn't matter if you're enabling or disabling them - either should promt you to restart the game to apply the changes)
3. When a message pops up prompting you to restart the game, do so
4. The game will exit and attempt to restart, but some way through the loading-bar sequence an error message will pop up stating: "Error compiling shader PSCollimator" and the game will fail to restart
5. Manually start the game again via Steam or the launcher and no error appears during the loading sequence.