For the past month or so, our Windows Vista PC has been "talking" to us by itself. It will be at the login screen with the monitor off, and sometimes you can hear somewhat of an ad playing when no one is using the PC. I restarted the PC and left it as is, and after 2 hours, it randomly starts playing whatever its wants. It's kind of creepy at times, and I'm not sure if it's a virus or some weird thing Microsoft added in some update. Can someone help me out with this?