HI Nat
Many thanks for your rapid response to my query. I can confirm that, when first installed, I was able to drag and drop single or multiple files into any of the three windows including the time line. However, this what I can no longer do. I take the first three steps you have listed above but, as mentioned, from then on I can only add files by double-clicking one at at time and then transferring clip window to the viewing window or the timeline.
As you suggested I have also uninstalled and reinstalled the set up file that I downloaded from the NCH site but with no change. It was downloaded and first installed on 19 Aug 21. It is shown at being file version 0.0.0.0 which is a bit puzzling - to me at least. I did not try downloading the setup file a second time. My runs Windows 10 (64 bit) and is moderately speedy with lots of storage. I have noted that my VP is shown at the top of the screen as being a Beta version but fully up-to-date. However, although I did not notice at the time this would have been the version which ran on my first installation. I've run out of ideas for anything else to try. It's disappointing as I was so impressed with functionality an ease of use of VP compared with my old video editor.
Richard