andyt and CaptO, thank you for your suggestions. Further update - I have now installed (successfully) Linux Mint and it operates quite happily save for a screen caveat that there is "software video acceleration only" and, therefore, there will be more activity (or something similar). Just wondering if this would point to problems with the video card as the source of the problem. Have ordered a new one anyway and at least that should prove a point one way or the other.
