Hi again. No external hard drive unfortunately, or not any more, and can't find a " linear" option to test. What does it come under? Can't find it under diagnostics, utilities or interactive tests. One worrying development is that I started using an old decommissioned laptop someone gave me to try. The screen is bad, flickery etc, but I've managed to get a few good hours out of it. I put a USB that I use a lot into it and Malwarebytes gave 3 warnings. I figured it just didn't recognise the drive so continued to cut a folder from the desktop onto the pendrive and this one has now blue screened a few times with Unmountable Boot Volume, but I don't know what state it was really in when the previous owner stopped using it, but maybe I have a virus on the USB. If you can direct me to this linear test, i'll see what it says. Thanks again! David.
