While I'm rummaging through buildings and such, my game will suddenly lose its sensitivity to the left shift button, which I have assigned to the run/walk function. Typically I will move about with the slower movement and use it when I want to speed up, but it seems that while I'm going in and out of buildings a lot, it will cease to detect me pressing the key. I have the toggle for the function set to 2x Left Shift, and it won't detect that, either. The only solution for this that I've found is to exit and reenter the game, but this has proven to be a temporary fix as long as I'm still searching buildings and such.