I have noticed this also. Although nothing pops up on my screen, I do see on the status bar at the bottom "waiting for ww.free20.com" everytime I go to a posted message, etc. I am using Firefox 22.214.171.124...and I dropped off a w from the address so it does not post as a url.
Edit: I did do a browse through my installed cookies and did find a cookie named free20.com. I deleted this. Hope that gets rid of the problem.