My system is on 24/7 and I use a screen saver which activates after 15 minutes of inactivity. Every now and then, when I first start using the system in the morning, there is an unknown icon in the Taskbar (image below). Usually, the appearance of this unknown icon will cause the system to become unstable and clicking any desktop icon will lock on it, but it will not activate or run the associated program. This usually requires a system shutdown using the On/Off button to correct the problem. However, when the icon appeared today I received an error message, after moving the mouse around; "System Settings Broker has stopped working"

Anyone else having this problem or know what may be causing it?

Click image for larger version. 

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I have enlarged the image from its original size for clarity.