Q:

How to escape obnoxious pop-up page?

I am using Google Chrome and somehow I stumbled upon an obnoxious pop-up on a webpage.

(Click image to enlarge) 
Basically, a dialog box opens up with only the option to click 'OK'. If you do click it, another box opens up with the same info, but this time there is a checkbox to prevent this page from creating additional dialogs. However if you do this and click 'OK' again, then the page refreshes (new window) and the process repeats. I have found that you can close it with Task Manager, but reopening Chrome will not allow me to escape without losing all my tabs.
How do I escape?
I use uBlock Origin on Chrome. I believe this pop-up happened when I was clicking links on ayumilove's page on Maplestory information.

A:

I JUST fixed an almost identical issue this week.  First the ANSWER, then the story.  
Do NOT click on anything, since whatever you see, (including the heading with the x) could be an illusion, activating a payload when clicking that PNG within another invisible window.  Instead, use one of these three methods. I've never seen this simulated X method, but it is certainly possible.

When the popup is in the foreground, which is likely all the time,
hit ALT-F4 as many times as you need to, which should close BOTH visible and invisible tabs/windows, until
you are back to normal.  Remember, there still could be some invisible windows
you can't see, but still click on, and need to close.
In Chrome only, go to Options, More tools,
Task Manager, and then find the offending window(s) and
close them.  Alternatively, you can use Windows Task Manager, or
Process Explorer to individually close all the offending windows.  First
sort the process list by time started, and your offending Chrome
processes should be the most recent.  Just close them one by one
until you think you've killed them all.
Completely kill ALL the Chrome processes you have open, starting
with the oldest process, which often will kill all the Chrome child
processes as well.  Then restart chrome.  It will complain that it
crashed and ask if you want to reopen the last tabs and windows,
which you should refuse.

Background story -- After ensuring that no other rogue processes were spawned about the same time as the window was opened, I spent about an hour trying to figure out how to safely close the windows without success.  I didn't want to trigger anything by trying to use the mouse in Chrome, because I know you really can't tell if the  X is a real windows button, or a simulated one that was from a superimposed PNG to look like a window you could close. 
An engineer walked by and first tried clicking on the X, which didn't work.  After I told him that the X could have been part of a fake .PNG, he agreed that could have been a mistake, triggering the payload.  Then he just hit Alt-F4 a number of times, closing all the windows until it was clear, and the sound also stopped.  Task successfully completed. 

