Found a cure a very small utility called hidevolumeOSD.
Do search for Hide Volume OSD and it leads to a website WordPress.Venturi.de which despite the de is in English. Installed and been running for a few days with no problems.

I think it is caused by introducing the MediaTransferControls interface message processing: https://www.ventismedia.com/mantis/view.php?id=14240

Workaround is to remove MediaMonkeyMT.dll from the MediaMonkey install folder.

Thanks.
I've seen a post online that the volume control is windows but the rest is because the program requests it. This would match with the change only happening when I upgraded to MM5.

There was a discussion on this and the conclusion was that this wasn't possible. The popup you see is from Windows and not MediaMonkey. You may want to check if Windows forums have a solution to disable it altogether.

Since moving from version 4 to version 5 pressing the pause key on my keyboard displays a large black box which shows the volume control, forward backward and play symbols plus the name of the track and the artist.
I don't want these, is there any way to stop this being displayed?