I have a MacBook running OS 10.5.8. I have Font Book in my Applications folder. I want to activate a certain font. Through my HD icon I navigated to Font Book. I selected the font I want to activate and then clicked on the "+" button at the bottom and a pulldown menu came down asking me to select a folder for the font. I selected one on my desktop and clicked "open" but nothing happened and the font was not added. What's the problem? Another problem I am having is that I keep getting a pop-up for MacKeeper which I guess is a virus. It appears in different forms. How can I make this go away?