Baffling error in Background worker code

[Zomalaja]

Your problem is almost definitely because you're trying to edit a My.Resources image

I'm editing a copy of a copy of the my.Resources image. I can do that successfully in a timer tick.

DOJ = My.Resources.Images.Don
Destination = DOJ

I'm changing the bitmap "Destination", 2levels away from the resource image.
The bitmap "Source" is a copy of the corresponding resources file, 1 level away

Destination.SetPixel(X, Y, Source.GetPixel(X, Y))

Nothing tries to alter the resource images