Have you tried updating video and sound drivers? Turning vsync on or off? Updating windows? Disconnecting unused controllers? Updating the firmware/drivers for the controller if you're using one? (This really sounds like a phantom input situation, but it's hard to say.)Maybe I need to explain myself better: when the game "stutters" it isn't frozen on my computer, it's still responding, the problem is that from one moment to another the aim goes flying around the screen, almost like someone had suddenly turned the sensitivity up for just a millisecond. Maybe it is a specific configuration on my machine, it could very well be, but my machine is as default as default can be.