Unwanted behavior with the MouseLook script

Hmm, I have no experience with scripting, but had to have the MouseLook script for the control of my character.

The thing is that every time I press forward to walk, the mouse aim resets to the horizon! This makes a visual jerk.
How do I turn it off?

I have Blender 2.61 and:

MouseLook.py Blender 2.55

Adapted by bill from 2.49 source at tutorialsforblender3d.com