I did everything you said the screen resolution cut off left side corner. The right side corner wallpaper is fix but it still cut off at left side corner.
If it's just the wallpaper that is affected, then double check to make sure that you have Fit selected for the "Picture position" like in step 9 of the tutorial below.
The wallpaper is stretch all the way out on left side corner I can't see windows 7 start all program button. I see a black border on right corner by the way the screen resolution say 1280X720.