If you hit the arrow that goes "back" to the same page that loaded the popup, it will load again every time....the command is embedded in your cached page.
You have it hit refresh to load the same page again without the command.
Hit back twice and it will come back.
Get it?
Let it load the ad then refresh the page and don't go back. Then close the ad.
That's what i have to do on Droid browsing m dot or www dot