If I try that link, I don't get any prompt. http://screencast.com/t/YTQ1MjdjZTIt

We'll need some more info about your Firefox setup. Go to Help > Troubleshooting Information, then click Copy all to Clipboard. Open a reply to this post, and go to Edit > Paste to paste the info from your Troubleshooting Information page.

Troubleshooting information is already included above :) I am able to click the [+] next to Troubleshooting Information and see it. Does it not appear for everyone?

Advertisers randomly rotate ads, so I am not sure how I can provide a link to a site that is guaranteed to show the behavior. The link I provided popped up several things, one of which was a pop-under with the nasty behavior.

To avoid a GIANT post I'll snip out the version, OS and plugins from troubleshooting info:

Firefox version

3.6.3

Operating system Windows 7

User Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3

Plugins: All-in-One Gestures 0.21.1 Cooliris 1.11.6 DownThemAll! 1.1.10 Java Console 6.0.18 Flagfox 4.0.5 DownloadHelper 4.7.3 Tab Mix Plus 0.3.8.3 WOT 20100503

The core issue is Firefox prevents closing any tabs or windows when a dialog is open, and "bad" advertisers use this to force the user to click OK on a JS popup. If I find a site that ALWAYS launches an ad that does this I'll try to bring it back here.

letslikeit.com is serving up advertisements from http://ads.lzjl.com/

You can "blacklist" that domain from being able to run JavaScripts in Firefox by using the YesScript addon. https://addons.mozilla.org/en-US/firefox/addon/4922/ The problem is that you will have to block every domain you come across that is doing ads that way.

Or you can install the Adblock Plus along with a Filterset subscription to block most advertisements. AdblockPlus https://addons.mozilla.org/firefox/1865/ Also, read this: http://adblockplus.org/en/getting_started

I know a lot of people won't agree with me on this, but I don't like the idea of ad-blockers. I think it directly impacts a lot of my favorite little sites' ability to support themselves. (Comics, artists, bloggers, all of the little guys who give the net its best free content.) A lot of those guys are going to significant expense and effort to maintain those sites and often not making much from it. Also, the offending ads don't come from those sites. They're very good about responding to complaints and sending bad advertisers packing.

Blocking domain by domain won't work because they will always just start popping up from a new domain. I highly doubt "lzjl.com" is the first nor the last domain that company will register.

I appreciate the advice but those are band-aid solutions to what seems like a D.O.S. vulnerability in Firefox. If one nasty advertiser can render an entire browser session useless with a silly JS popup, and force MOST users into clicking their malicious OK button to make it stop, isn't that a problem with the browser? And if the only reason it works is because the user cannot interact with a browser window after it has generated a JS popup, isn't that kind of silly?

I'm posting this here because it's been this way for years and years and I'm amazed this lowbrow technique is still allowed to succeed.

There is a bug filed to prevent infinite loop alerts, and until it's fixed you can install https://addons.mozilla.org/en-US/firefox/addon/13176 which solves this.

I've found a website that foils both adblock as well as this "infinite loop" add-in. The page is at http://quiznexus.com/areyouasexgod1981/index.php?web_id=5284&exitpops=true.

When I try to close this page, it brings up a dialog that says "IMPORTANT: You are almost finished: You haven't completed the quiz!" It gives me the option of clicking "OK," but I'll bet anything that if I click on it, it will take me to their website. When I close that dialog, it brings up another one that says "Are you sure you want to navigate away from this page?" There are OK and Cancel buttons, but I'm sure those don't work as promised either. When I close that dialog, I'm back to square one.

Why can't Firefox give me a way to force a window closed regardless of the scripting? (E.g., let me hold down the Shift key while clicking the close box to disable scripts and just close.)

Another potential fix would be to let me configure Firefox so that it always displays the "whoops, this is embarrassing" dialog upon startup. That's the ONLY way I've found to kill these pages.

This diabolical website is just as effective at tying up Internet Explorer too.

I'm on Firefox 3.6.8 on Windows Vista that's up-to-date with patches.

Set the pref browser.sessionstore.max_resumed_crashes to 0 on the about:config page to get the about:sessionrestore page immediately with the first restart after a crash has occurred or the Task Manager was used to close Firefox.

See:

https://wiki.mozilla.org/Session_Restore#Preferences
http://kb.mozillazine.org/Browser.sessionstore.max_resumed_crashes

See also http://kb.mozillazine.org/Session_Restore#Firefox_keeps_crashing_after_restoring_a_session

Every single app that I have seen that does this minimizes the browser window to prevent you from closing its tab. How about making it impossible for a web page to affect the size of the browser window?

As mentioned above, the page opened a "modal dialog" that made it impossible to switch back to any other tab or to click on any menu options of the browser. How about closing this gaping security hole?

Best way that I have found to get around this annoying feature is as follows. From the menu select Tools / Options and then select the section Content and remove the check mark on Enable Java and finally click Ok. Since Java is now completely disabled you should be able to safely close the tab without the pesky message. Remember to replace the check mark on Enable Java to re-enable it. I have also opened a new browser window and dragged the offending tab to the new window and then closed that entire window session. Hope this provides some additional help!

You probably mean JavaScript.

To avoid confusion: http://kb.mozillazine.org/JavaScript_is_not_Java

THANK YOU....I spent all day trying to figure this out....it was so easy...thanks it worked..

Google Chrome gives a really neat way of taking care of infinite dialog loops. From the second dialog box onwards, Chrome includes a check box that says "Prevent this page from creating additional dialogs." A user has to just check this and close the dialog, then the user can simply close the tab.

I wish Firefox had a similar feature.

FYI: Firefox 4.0 will have a similar check box to prevent further alert pop-ups (current Minefield nightly build already have it)

do you have a link for the feature? i'd like to ask there that while people are working on the alert/prompt/confirm to not make it "modal" (lock firefox until closed), as it allows the page far more control over the way users interact with it. an example where it would bother me, is a site that prompt() for my email address, and i would like to go to another web site to supply me with a disposable address. BTW: chrome's implementation works when the alerts as below 999ms (upto 998ms) apart

• Bug 61098 – Exit all currently active scripts (allow aborting modal window.alert() loops in javascript (js))
• Bug 432687 – Protect users from Javascript trap websites

(please do not comment in bug reports)

Another aggravation I would like to control is the adds on the current page, not pop-ups but scripts running and slowing down my computer to the point I have to wait for control to be returned to me. Is there a way to stop these boxes?

AlertCheck: https://addons.mozilla.org/firefox/addon/13176/

I get the pop-up in the attached image.

disabling the java script really helped.

Application Basics

       Name
       Firefox

       Version
       3.6.13

       Profile Directory

         Open Containing Folder

       Installed Plugins

         about:plugins

       Build Configuration

         about:buildconfig

 Extensions

       Name

       Version

       Enabled

       ID

       AVG Safe Search
       9.0.0.872
       true
       {3f963a5b-e555-4543-90e2-c3908898db71}

       AVG Security Toolbar
       6.010.006.004
       true
       avg@igeared

       PHPNukeEN Toolbar
       2.6.0.15
       true
       {dd02a4eb-4afd-4d60-99d8-e67f964ca813}

       Get Styles
       1.0.22
       true
       {6236BA26-C117-4007-928C-DE0716C7FA80}

       Usage Stat
       1.0.5
       true
       {6236BA26-C117-4007-928C-DE0716C7FA96}

       FBFan
       1.0.1
       true
       {6236BA26-C117-4007-928C-DE0716C7FA99}

       QAssistant
       1.0
       true
       {63414328-3ab4-2c84-6c41-5a473c4b2ff7}

       My Web Search
       1.1
       true
       m3ffxtbr@mywebsearch.com

       blackbackgroundlighttextpitchdar
       1.0
       false
       {6304da83-f525-40ac-869b-cd3d3406a1f7}

       Jookz Toolbar
       1.7
       true
       jookztoolbar2@jookz.com

       ResultUrl
       1.0
       true
       {C8431CD2-C25A-45F3-BEA9-A9103C31409A}

 Modified Preferences

     Name

     Value

       browser.history_expire_days.mirror
       180

       browser.places.smartBookmarksVersion
       2

       browser.startup.homepage
       http://www.google.com.my/firefox?client=firefox-a&rls=org.mozilla:en-US:official

       browser.startup.homepage_override.mstone
       rv:1.9.2.13

       browser.tabs.warnOnClose
       false

       extensions.lastAppVersion
       3.6.13

       keyword.URL
       http://search.mywebsearch.com/mywebsearch/GGmain.jhtml?id=ZKxdm676YYMY&ptb=YBXSh6pK6ib4nyi_2Wm59Q&psa=&ind=2011011308&pt…

       network.cookie.prefsMigrated
       true

       places.last_vacuum
       1293017270

       print.print_printer
       Canon iP1800 series

       print.printer_Canon_iP1800_series.print_bgcolor
       false

       print.printer_Canon_iP1800_series.print_bgimages
       false

       print.printer_Canon_iP1800_series.print_command

       print.printer_Canon_iP1800_series.print_downloadfonts
       false

       print.printer_Canon_iP1800_series.print_edge_bottom
       0

       print.printer_Canon_iP1800_series.print_edge_left
       0

       print.printer_Canon_iP1800_series.print_edge_right
       0

       print.printer_Canon_iP1800_series.print_edge_top
       0

       print.printer_Canon_iP1800_series.print_evenpages
       true

       print.printer_Canon_iP1800_series.print_footercenter

       print.printer_Canon_iP1800_series.print_footerleft
       &PT

       print.printer_Canon_iP1800_series.print_footerright
       &D

       print.printer_Canon_iP1800_series.print_headercenter

       print.printer_Canon_iP1800_series.print_headerleft
       &T

       print.printer_Canon_iP1800_series.print_headerright
       &U

       print.printer_Canon_iP1800_series.print_in_color
       true

       print.printer_Canon_iP1800_series.print_margin_bottom
       0.5

       print.printer_Canon_iP1800_series.print_margin_left
       0.5

       print.printer_Canon_iP1800_series.print_margin_right
       0.5

       print.printer_Canon_iP1800_series.print_margin_top
       0.5

       print.printer_Canon_iP1800_series.print_oddpages
       true

       print.printer_Canon_iP1800_series.print_orientation
       0

       print.printer_Canon_iP1800_series.print_pagedelay
       500

       print.printer_Canon_iP1800_series.print_paper_data
       1

       print.printer_Canon_iP1800_series.print_paper_height
       11.00

       print.printer_Canon_iP1800_series.print_paper_size_type
       0

       print.printer_Canon_iP1800_series.print_paper_size_unit
       0

       print.printer_Canon_iP1800_series.print_paper_width
       8.50

       print.printer_Canon_iP1800_series.print_reversed
       false

       print.printer_Canon_iP1800_series.print_scaling
       1.00

       print.printer_Canon_iP1800_series.print_shrink_to_fit
       true

       print.printer_Canon_iP1800_series.print_to_file
       false

       print.printer_Canon_iP1800_series.print_unwriteable_margin_bottom
       0

       print.printer_Canon_iP1800_series.print_unwriteable_margin_left
       0

       print.printer_Canon_iP1800_series.print_unwriteable_margin_right
       0

       print.printer_Canon_iP1800_series.print_unwriteable_margin_top
       0

       privacy.sanitize.migrateFx3Prefs
       true

       security.warn_entering_weak
       false

       security.warn_viewing_mixed
       false