If I save the image on the problematic computer, it runs OK from then on.
Then, the error again shows up on another computer and behaves similarly -
if I locally store the image, it runs OK. The problem is when I start the
image that was copied from another computer. Of course I pay attention that
I don't have Pharo running in parallel.
Everything works well with older versions of Pharo images (5.0, 6.0, 6.1).