The problem is in the way the browser presents the modal dialog. Unfortunately, postbacks don't work in them. I've also noticed that it's very difficult to refresh a page that you are viewing in a modal dialog. I think it has to do with the way the browser gets the HTML for it. It's almost like it gets the page in the background and then paints the dialog with the contents. If you put a page that takes a long time to load, you'll see the delay very obviously in the time it takes the modal dialog to show up.