Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Looks like you have VoiceOver activated (although I’d think you’d be hearing that too)

Head over to System Preferences -> Universal Access and you can turn it off.
 
I've got another problem. How do I prevent the border of a textbox to be highlighted when I'm typing?
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.