Hi,
This really looks like poor polar alignment and or tracking error to me as all the stars are extended in the one direction. Another possibility is that your pier is not stable and when you walk close to it you cause it to move and then settle ever so slightly.
I am not sure why or how you can align your polar scope with the trapezium as this would imply that your polar axis is in the competely wrong direction. It should be pointing at the SCP.
Vignetting is drop off in light levels at the corners of the image and that is not your problem.
Maybe you could post your drift alignment procedure?
Paul
Edit, I guess you meant the trapezium in the polar scope and not the trapezium in M42, sorry
