Hello.
I have an abnormal blur all the time, even if I disable Motion Blur.
For example, I see leaves falling with excesive blur and enemies blurring even when they're only walking.

Maybe not a game bug, but your screen is slow? Did you checked that?

LCD panels are slow, comparing to CRT displays.

I have a cheap LCD TV that has that effect too... are you using a proper computer monitor? Is it old? What is its response time?