Telephone icon in the system tray

Sometimes when my kids are logged on the computer there appears a yellow telephone icon in the bottom right corner of the task bar and when you try to place the mouse arrow over this icon it quickly disappears. Is this something serious?

 

Sometimes an icon in the system tray that should have been removed earlier will disappear if you try to access it. Is it possible that this is to do with using voip or some other program? Google for "yellow telephone icon" and see what comes up. I found a few different possibilities and you might recognise one of them as something that you have on your computer. If you do, watch for a pattern of the icon being in the system tray and not going away when that program is shut down.

Other than that, I'm not sure what it could be. You could follow the intructions on this site for checking your computer over thoroughly and checking that you have appropriate security software on your computer. The links are here:

http://forums.majorgeeks.com/showthread.php?t=35407
http://forums.majorgeeks.com/showthread.php?t=44525

Hope you find the answer.