Oh yeah, another one.
The Suffering: Ties That Bind. A pretty mediocre sequel to what I found to be an enjoyable game overall, but I was pretty hell-bent on beating it with the best ending I could manage. That is, save all the important NPC's and generally be an upstanding guy.
The prison warden, while escorting him, ended up stuck on top of a computer console and wouldn't budge. I tried moving to another room in the hopes that he'd follow me but when I did it auto-saved, and when I went back he was dead. With no enemies around. Motherfucker.
The second glitch, during the same game, was similar; I tried to kill a boss while this scottish dude was trapped in a wall of fire. The guy RAN OUT OF THE FIRE and dashed into another room, wreathed in flames and running around in circles screaming "JAYSUS CHRIST" and "WHY WON'T YOU SAVE ME." Even after beating the boss he kept doing it.
Whats worse is that both counted as being killed, so no good ending.
Not that I could BEAT the game, since the final boss was a combination of teeth-grindingly difficult and bug-ridden instant-death mess.