Then the phone call with Apple. We took screenshots, went through this and that but nothing makes the CD drive work. We did fix something that got set up wrong with the back-up drive, so that's good. Meanwhile, we're now going to try the one thing we haven't. I went to Amazon and bought a powered hub - because we've read that these ports don't get enough power for the USB-C - it's arriving between five and ten and I'll know instantly if that's been the culprit all along. It would make sense that my 2015 iMac also wouldn't ultimately recognize it, although it did when I first got it - I wouldn't be surprised if they lessened the ports on one of the OS updates on that - but the joke is, it still works just fine on the 2010 laptop. None of it makes a lick of sense to me. But I'm hoping the powered hub works. I don't really need its extra ports, but it's worth it if we can get the CD drive to work. If not, I can return the hub.