Do you have Adobe Reader installed on your computer by any chance? Adobe Reader adds its PDF reader plugin to all browsers by default. To remove the plugin (if it was installed by Adobe Reader), uninstall Adobe Reader from the Control Panel.

Is the problem that Firefox is discovering two different versions of the Adobe Acrobat plugin, an older and newer one? If you type or paste about:plugins in the address bar and press Enter, Firefox should displayed detailed information about all your installed plugins, including their exact location on disk.

I now have all Adobe plugins disabled, but the problem is still occurring.

I have both Adobe Reader XI and Adobe Acrobat 9 Pro installed on my machine. This problem is specific to Firefox. I do not see it if I use other browsers. I thought that the problem was fixed, but it is not. It appears to me that the browser is trying to run an Adobe Flash advertising video, but it is blocked, resulting in the display of a large black box. Why is it that one must jump through hoops in order to use Firefox?

Can you give a link to the page that is generating the black box?

On other browsers, does a video appear and play there instead of showing a black box?

The page is always the same: CNN.COM. I first noticed this problem several months ago. It went away for a while, then returned last week. Coincidentally, it reappeared right after I installed an update to Firefox.

On other browsers, what appears near that box is a video advertising, most recently, the Acura TLX brand of new car. However, the video does not block any of the CNN home page on other browsers. It pushes the rest of the page downwards, runs for a few seconds, then minimizes. It appears to me that Firefox is not able to properly handle the Shockwave Flash that is trying to run.

Here is the HTML that I believe is the offender:

<embed name="prpswf" src="http://speed.pointroll.com/PointRoll/Media/Panels/Acura/874034/Mullen_AcuraTLX_Thrill_970x418_Auto_03.swf?PRCampID=62841&PRPubID=cnn&PRAdSize=970x90&PRFormat=PE" flashvars="PRImpID=B01205007612031C030F57900FEA0101&PRPanel=-874034&PRCID=1962846&PRPID=2579160&clickTag1=http://clk.pointroll.com/pc/?p=-874034%26c=9001%26i=B0120500-7612-031C-030F-57900FEA0101%26clickurl=http://adclick.g.doubleclick.net/aclk%25253Fsa%25253DL%252526ai%25253DBMZIPjF0cVbXzA4a_lALFsIHoCp2F9ZEGAAAAEAEg9fzNHjgAWPWYrbfpAWDJhoeLvKSgGrIBC3d3dy5jbm4uY29tugEJZ2ZwX2ltYWdlyAEJ2gETaHR0cDovL3d3dy5jbm4uY29tL8ACAuACAOoCFS84NjYzNDc3L0NOTi9ob21lcGFnZfgC8tEekAOsApgD4AOoAwHQBJBO4AQBoAYW2AcA%252526num%25253D0%252526sig%25253DAOD64_12aZ7MLNknUo3_oQXa9QiItQX_9w%252526client%25253Dca-pub-2855247441935805%252526adurl%25253Dhttp://ad.doubleclick.net/ddm/trackclk/N8821.146.TURNERNETWORKCNN.COM/B8637477.116766408%253Bdc_trk_aid=289732826%253Bdc_trk_cid=62219350&prVideoName=970x418-waivers-cnn-h264_default.mp4" wmode="transparent" quality="high" menu="false" allowscriptaccess="always" allowfullscreen="true" type="application/x-shockwave-flash" style="height:418px;width:970px" height="418" width="970">

I had to disable NoScript to get the ad. After that, it works normally (screen shot attached showing the area that pushed down). Do you use any extensions that might affect ads on web pages? You could try disabling them and see whether that makes any difference.

Adobe PDF Reader and Acrobat probably don't have anything to do with the problem that you're having with CNN.

Okay, then what is causing it, and why don't the other browsers have the same problem? Shockwave Flash has to be activated before it can run in my browser. I am asked every time I wish to play a Flash video, but not on the CNN Web site. It just tries, unsuccessfully, to run, resulting in the black box that obscures a good portion of the CNN home page.

I have my setting for Firefox almost exactly the same as my settings for Chrome. No problems with Chrome, however.

I had asked about extensions. Do you want to test the page in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any difference?