Matt Laur , Jul 29, 2008; 09:21 p.m.
Your browser is being asked to fetch an ad from that address, and the page doesn't consider itself done until it has. Depending on the browser you're using, try hitting ESC (the escape key) or click your browser's STOP button so that it gives up on that fetch more quickly.
While photo.net does have the choice to run, or not, ads from that source, they can't control when that third party's web servers, or your path over the internet TO that web server, is slow or broken. So, tell you browser just to stop. That usually does the trick.