Further to my own posting; I do have two DVD drives but the correct one is being chosen each time. I have of course tried several different blank discs from the pack I bought.
One interesting thing however, I recorded data onto one of those discs using an alternative source and then tried it on my PC with DVDFab Platinum.
The software recognised the disc without problem and I could see the playback in the review window.
I also successfully played the disc using a different media player (VLC).
However, when I try to use one of those blank DVD+R discs with a variety of software including DVDFAB Platinum, I get a message along the lines of â€“ â€˜No media detectedâ€™ or â€˜The disc is not empty.â€™