I'm modding the ini to get the game into 1600x1200 - turning off bloom didn't fix the problem, just altered it a little. Turning off post-processing, but leaving on bloom, seems to have fixed everything.
I'm considering turning it back on next time I play thru the game, as it was a pretty cool effect. This is what the world sort-of looks like if my glasses are really dirty, which makes the game more horrific when turned on - maybe the protagonist also has bad eye-sight, in addition to his below-average melee skills…