My problem appears to only have annoyance value but I am afraid it could have some long-term effects. Has anyone else had this problem? Going back many years one could download such screen savers and I suspect this bug is something similar. It takes the appearance of a ghost-like blob which starts randomly moving around the screen and is visible on my latest chrome browser V 56.0.2924.87 (64Bit) and on my desktop. I have attempted to screen shoot the thing but have not succeeded so far.
I will follow up as soon as I succeed in taking a screen shot of it. Many thanks. Graham Chapman.