OK, I ran some more prints and the problem persists, with and without "advanced printing features."
Another forum suggests that the problem might be with my USB cable. If memory serves, I've had the problem with other cables and even Firewire, but I might change them around anyway. Maybe get a new USB board AND new cable. I suppose they're not too expensive. (No more that three or four sheets of Innova paper!)
Maybe my motherboard has a problem with its USB function. All my other USB stuff works as it should but sending big files to a printer always seems to test the computer's resources.
We'll see...
By the way, thank you all for your quick responses. MB