User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:13.0) Gecko/20100101 Firefox/13.0 Build ID: 20120601045813 Steps to reproduce: I went to a form page and fill them out. Then I wanted to go back (Back button). I was sought as to whether I will remain on the site or would like to leave the page. No matter what I click on it, this request does not go away. Actual results: Only a reboot helps via the Task Manager. Expected results: The browser has actually leaving the page

It would help if you could provide the url of the form. This doesn't appear to be security sensitive unless the form is private or confidential. I'll wait to flip the security flag until David replies.

Did you try anything other than going back? If you reach some pages by a scripted redirect the page you think of as the previous page is really two or three pages back. Going "back" will take you to a redirect back to the same location. You should, however, be able to leave the page by putting a new address in the URL bar, clicking a bookmark, or closing the tab. You'll get the prompt saying the page would like to you stay, but should be able to leave if you click the appropriate choice.

I can't be sure without an example or testcase, but this is probably a site chaining a few onbeforeunload tricks (tracked by https://bugzilla.mozilla.org/show_bug.cgi?id=432687).