Ed —
I’m also seeing this same error so wanted to pitch in what I am seeing with a little more detail. Like the others, I’m only seeing this in Chrome, both on PC and Mac. I’m also led to believe this may be due to some update in Chrome, because I’m having this issue on a site that was not touched for close to a week and is suddenly having the scrolling issue. I’ve also seen this issue in multiple versions of Dante.
A quick fix for now is to change fixed background to scrolling, which although it disables the parallax for the moment, it does allow the backgrounds to load properly. Hopefully any of this can be of some help.