Over the weekend I found that the mouse icon had the continual circling image around it suggesting that there was background activity. This extended to flickering of the background when on the internet. I established that Norton Internet Security exe was at the top of CPU usage.
I contacted Norton about this and the upshot was that by changing the mouse pointer to the default setting it resolved the problem!!
The mouse pointer had been previously set to Extra Large.
Anyone come across this before as I found the cure as being strange?