I've already posted about this in two other Mac forums and been to the Genius Bar, and everyone appears stumped. Posting here on the chance that someone has a clue what's happening. At random times of the day, something will appear under shared networks that has the URL of some website. Here's a recent example: http://tinypic.com/view.php?pic=ejx1df&s=4 Sometimes this is a site I recognize and have been to, but sometimes it's completely foreign to me, and in one instance it was obviously a tracking site (b.scorecardresearch.com). I know that other computers can show up as shared when others are connected to the same router, but I don't understand the appearance of URLs. These seem to come and go at random times. I've been monitoring it closely and I can't link it to anything I'm doing. However, they seem to go away when I switch over to another wifi network (my neighbor has an open one that I can test), and they never appear when I'm using wifi away from home. Even weirder, there are three other Mac users in my house that connect with the same wifi router, and these phantom networks don't show up on their systems while they're on mine. Since noticing this, I've tightened my wirewall settings just to be sure, and I ran Macscan twice, which found no threats. I've had no issues with my Macbook's performance and it seems to be benign, but it still weirds me out a little. Has anyone ever seen this before or know what might be causing it?