We need a bit more information such as: When did this begin to happen - suddenly, from day-one, etc.? Does this happen regardless of the project? Did you recently update any drivers or change any hardware? Can you restore your system to an earlier date when it did work?
Many thanks for your contributions.
I use a Microsoft wireless mouse.
This problem did not occur for me in SV12.
In the previous post "Clicking Master Audio Fader freezes mouse", a temporary solution is given as "When the mouse action freezes after clicking on the Master Bus, press Ctrl+Alt+Del then click on Cancel"
This worked for me and the Master Bus setting could then be changed with the mouse, but you have to repeat it each time you restart SV13.
Surely we should not have to do this.
Please Mr Sony, get this fixed in your next update.