I have noticed that since installing DisplayFusion when I right click on the start button I still see the Power User's Menu but none of the tasks (e.g. control panel) will actually open when I click on them. Is there a fix or a setting to correct this?

Very good point Keith. I run Display Fusion on start-up and it is then running in the background. I have just gone into Task manager and stopped DF from starting and .... no, the right click still doesn't work! So I need to look for another reason.
The reason I thought it was DF was I had to do an enforced re-install of Windows 8.1 and before I loaded DF the right click on the Power Users Menu was working fine. Immediately after loading DF it stopped working (as did the Windows + X command). As I understand it DF also has it's own task bar so I put 2 and 2 together and seemingly made 5!!
So, the search for a solution goes on.
Many thanks for your reply and the suggestion - which hadn't occurred to me to try.