MY PHONE IS DOING THE EXACT SAME THING! Do you also get the voice that says "Congratulations" as it pops? And the Wal-Mart "You've won..." pop up? Which server do you use? I use Sprint.
It is so frustrating! I haven't gotten the voice or Walmart pop- up yet. Only Angry Birds pop-ups. I use at&t unless I'm connected to wifi at home and that is through fidelity (our local phone company)