This is what I did: I had the earlier version of (working) eset sysrescue on my USB. And since you've given me the link to the latest ESET USB creator, I've recreated the partition of my USB stick and reformatted it. Then I ran the eset creation tool again. And after the program completed the progress of downloading the image, when it was due to write it on the stick, it issued that error window and stopped. I have a Kingston USB stick of 16 GB, so I don't think it is a problem with it, especially as it ran the previous version of the sysrescue disk fine.
Any suggestions please?