The mouse/cursor is behaving erratically for no apparent reason. On boot up to the 'welcome' screen it sits at the bottom left of the screen and cannot be moved away from there - although it tries to respond to mouse movement.
When all programmes are loaded it moves to the top left of the screen. It can be moved from here but only if I am quick to select the icon I need - any pause and it goes back to the top left of the screen. I am using a trackball Logitec Marble mouse which, to date, has given no trouble. I have unistalled the software and re-installed it. At first all seems normal until I boot up again and then the cursor reverts to its top left position.