Many malicious programs are using various techniques to try infect your computer. While we are actively pursuing new ways to defend your computer, an inadvertent mouse click may be all that stands between you and a major problem.
Consider the graphic. If you were to click the red ‘X’ to close the window, you would have ended up installing the virus instead of closing it, clicking anywhere on that window will actually cause the payload to hit – the whole thing including the title bar is a linked graphic. The mouse cursor may even change to the active link pointer, which would be a clue that there is something sneaky going on.
How can you safely close these unexpected windows without messing up your computer? By simply holding the ALT key and then pressing the F4 function key, you would safely close the window.
The key point is to train yourself to use ALT+F4 to close open windows.