From what I've seen in my travels across the Internet, my problem seems to be unique: After buying GTA IV on Steam several months ago and finishing the main plotline, I became bored with the world itself and decided to download some things to make the game a bit more fun. Here's where my problem comes in. At some point during my modification binge, I must have tweeked some config files somewhere (or installed something that tweaked them for me), because now the pedestrians are pretty much insane and I can't find a way to change them back.
Insane, you ask? OK: when driving on the road, it is not uncommon for said pedestrians to pull their cars over - as they would if gunshots were fired - and hop out of their cars to pull their passengers from their seats to start fistfights with them; hotdog stand owners are frequently found chasing customers up and down the block to feed them knuckle sandwiches. In shadier areas, prostitutes fight their pimps and criminals have gunfights with each other and the police whenever their vehicles cross paths. If I allow myself to get a wanted level, most of the personnel coming to detain me are more preoccupied with pedestrians in well-populated areas than they are with me.
All of this wouldn't be such a pain if it wasn't for the fact that the trainer I downloaded required me to start a new game, and I'm stuck on one of the early missions (before the rest of the city was opened up), and for some reason the porn shop guys won't be intimidated. Probably something to do with their newfound fearlessness. I can't even buy clothes or go bowling because the clerks are always running outside to dish out their own crazy brand of justice.
Sigh... anyone know what the problem could be?