Display problems in Firefox

Recently a couple of readers contacted me, noting that they couldn’t see any comments on my site in Firefox. In the main column, anything below the actual post content just didn’t show up. On the home page, nothing below the intro to the first post was visible. Other browsers display the comments as expected.

What seems to happen is that if a page contains an object element, that element and anything that comes after it in the source code is not displayed. When I asked the people having this problem to check the source code of the pages, they reported that everything was there. It just wasn’t rendered on screen. Very strange.

At first I thought it could be some odd CSS problem, but since I haven’t been able to reproduce the problem myself, I didn’t really know where to start looking. Then I got a report from one of the readers that were having the problem that trashing the user profile had done the trick, and made the comments and the comment form visible.

That made me start thinking of what could corrupt the user profile, and one possible cause could be upgrading from a Firefox pre-release to 1.0 without uninstalling the older version first.

If that is the case, many people may have problems with their Firefox installations without noticing it. This theory is backed up by my AdSense statistics since the release of Firefox 1.0 (I use an object element to load the ads in XHTML capable browsers).

If you load this post in Firefox 1.0, and see no Google Ads (unless you’re blocking them, obviously), no comments, and no comment form, your Firefox user profile is probably broken, and you need to trash it. Well, the entire profile isn’t necessarily corrupt, but I don’t know exactly which file is causing the problems.

I really appreciate it when people leave comments around here, so it’s a shame if a lot of you can’t read other people’s comments or post your own. It would be great to sort out exactly what causes the problem, and if it can be fixed without trashing the entire user profile. Removing the object element or serving my pages as text/html could fix the display problems, but I have no way of checking if it does. Besides, even if it did help it would be a really ugly workaround.

Anyone have any ideas?

Update (2005-01-23): The AdBlock extension for Firefox is causing the problem, not corrupted Firefox user profiles.

Apparently it has problems hiding an object element. There are workarounds (see the comments), but AdBlock is broken, not Firefox or my site.

If you use AdBlock to hide Google ads and would like to read or post comments here, please set AdBlock to “Hide ads” instead of “Remove ads” until the AdBlock extension has been updated.

Update (2005-01-26): The problem has been fixed for the next version of AdBlock.

Posted on January 23, 2005 in Browsers


  1. In my Firefox everything is all right. I uninstalled the older version of Firefox before installing the final, doing not so could be the cause for the problems you mention.

  2. Well i archived the prefs i trashed. But i wasn’t able to reproduce the effect with the old prefs. I stored them for keeping the bookmarks and plugins. I did manage to keep the bookmarks, but i did need to download and reinstall all the plugins.

    Your idea about pre-release versions of Firefox seems to be a good one. I started with version 0.8 i believe, so it’s a pretty logical conclusion. I just hope it is correct.

    I’m also interested to know if someone else is able to find the file in the prefs that is causing this. I couldn’t find anything on the subject on the mozilla forum.


    I have been having a few probs with my computer. Apps seem to quit on me all the time. I haven’t founc out why yet. Firefox did unexpectly quit on me again. And after viewing this site again i saw i had the same problem again.

    Which leads me to one conlusion, i doesn’t have to do with older pre-release versions. After an unexpected quit, it seems to corrupt a file. The file i found to be causing the problem. (on OSX) User> Library> Application Support> Firefox> Profiles> “profilenumber”> chrome> overlayinfo> browser> content> overlays.rdf

    This is the content of the file.

    <?xml version="1.0"?> <RDF:RDF xmlns:c="http://www.mozilla.org/rdf/chrome#" xmlns:NC="http://home.netscape.com/NC-rdf#" xmlns:RDF="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <RDF:Seq RDF:about="chrome://browser/content/browser.xul"> <RDF:li>chrome://adblock/content/adblock.xul</RDF:li> <RDF:li>chrome://disabletarget/content/disabletargetOverlay.xul</RDF:li> <RDF:li>chrome://gm-notifier/content/gm-fb-overlay.xul</RDF:li> <RDF:li>chrome://webdeveloper/content/menu.xul</RDF:li> <RDF:li>chrome://pagerankstatus/content/pagerankstatusOverlay.xul</RDF:li> <RDF:li>chrome://targetalert/content/targetAlertOverlay.xul</RDF:li> <RDF:li>chrome://fangs/content/fangsOverlay.xul</RDF:li> <RDF:li>chrome://livelines/content/livelines.xul</RDF:li> <RDF:li>chrome://bugmenot/content/bugmenotOverlay.xul</RDF:li> <RDF:li>chrome://useragentswitcher/content/menu.xul</RDF:li> <RDF:li>chrome://sage/content/sage-Overlay.xul</RDF:li> </RDF:Seq> </RDF:RDF>

    Love to hear any conclusions one can draw from this. I don’t know what is means. I’m just glad i know which file i need to trash next time.

  4. Ok, one more update. I just dicovered by removing the file, my extensions didn’t work anymore. The one that causes the problem is Adblock I disabled the extensions and relaunched Firefox, and everything works as it should again.

    And i believe the Adblock extension caused the unexpected quit in the first place.

    Roger which extension version of Adblock do you use? The whole idea that an extension can cause you page not to display right seems alarming to me.

  5. January 23, 2005 by Roger Johansson (Author comment)

    Med: I’m using the same version of AdBlock, Firefox 1.0, Mac OS X 10.3.7. I don’t have AdBlock configured to block Google ads though.

  6. I’m using Firefox 1.0 with a profile from 0.8; therefore, I’m guessing its a problem with some older version of Adblock, as I don’t have that installed.

  7. It’s definitely a problem with older versions of Adblock. I disabled mine (Adblock v0.5 d2 nightly build 39), now comments are visible. Strange…

  8. I had reports of my entire blog page not displaying to certain users running Adblock. I also use the object method and my ads are at the top of the page so this may have been the same problem as you describe.

    I was able to resolve it by surrounding the object tag with a floated div, although I have no idea why this worked. It appears to be a problem with Adblock.

    See this forum topic on my site for more information.

  9. January 23, 2005 by Roger Johansson (Author comment)

    Chris: Sounds like the very same problem. I’ll try your floated div trick. A hack, yeah, but if it lets people see and post comments I figure it’s worth it. Besides, the ads already are in a div here, so I’ll just need to float that.

  10. January 23, 2005 by Roger Johansson (Author comment)

    Bah. I just changed my mind. AdBlock is broken, not my site. I added “adsense*” as a blocking string to AdBlock, and now I can see the effect. Everything after the ads is gone.

  11. Bonzer guys, glad to a a zillion web-design gurus made short order of that problem. :) I was tearing my hair out as I had just reinstalled my system to begin with. =D

  12. January 23, 2005 by Mariano

    I made the update from the Pre Release to 1.0 and I lost almost all my bookmarks. Just left two folders and 15 links. That’s like the “best navigator” works.

  13. Better than the AdBlock extension is to implement as user style sheet which filters out ads.

    @import url(http://www.lashampoo.net/unix/stopADVbanners.css);

  14. I’ve got “Adblock v.5 d2 * nightly 39” and I don’t see any ads, but I do see comments. And always have…

  15. I upgraded to a nightly build of Firefox earlier from 1.0, and it still seems fine. I have no clue how that could happen.

  16. I have adblock set up to block google ads, and “Remove Ads” is selected, but I’ve never had any problems reading the comments on this site. However, I don’t use the string “adsense*” to block it, as Rojer described. I’ve always used the URL: http://pagead2.googlesyndication.com/pagead/ *

    (Note: The space before the wildcard “*” is only there to prevent it being removed by this comment system. To use the URL in Adblock, include it without the space)

  17. January 24, 2005 by Roger Johansson (Author comment)

    Seems like it all depends on the string you use to filter out the ads. Using the URL Lachlan mentions works fine: no ads, but comments are there:


    (To include a literal asterisk in a comment, escape it with a backslash: \*)

  18. I didn’t even configure Adblock. I was about to, when it crashed on me.

    I just hope we don’t have to start designing for extension dependancy.

  19. I only go as far as: http://pagead2* and have never had any issues I just get a large blank area where they have been removed suites me fine.

  20. I have never had a problem blocking anything with adblock. I’ve been using Filterset.G for some time now and I’ve been able to block google ads and post and see everything.

  21. Roger: the reason that “pagead2” or “pagead/*” work is that the bug is caused by blocking the URL of the element — in this case, “/inc/adsense_336x280.php”. Blocking “pagead” just removes the iframe that the <object> loads.

    Adblock does occasionally expose inconsistencies in Gecko, especially when dealing with stuff that isn’t actually rendered by Gecko: applets, plugins, and, in this case, <object>s.

    Unfortunately, the issue here appears to be a side-effect of Adblock telling Gecko not to download the content of the <object>. Thus, the actual bug is within Gecko itself; it’s just that the buggy code is only run when a user has Adblock installed.

    From Adblock’s perspective, the only way to fix the rendering bug is to download the content of the object, regardless of the user’s settings. Unfortunate. In any case, this has been fixed for the next version of Adblock.

  22. January 24, 2005 by Roger Johansson (Author comment)

    Ben: Thanks for the explanation. I tried forcing the problem to appear without AdBlock being active by removing the object URL, but that didn’t cause the problem with disappearing content. I suppose AdBlock works in a slightly different way.

    Either way, it’s great that a workaround has been implemented. Thanks for letting us know.

  23. January 31, 2005 by Bobby Snow

    OUR computer keeps bloking us from letting us surf the web I’m thinking that it was a viruse. But, it wase’nt I lauched 4 programs at different times and the resolts all came out different, so I thought that there was virisius getting through the recoverd ‘holes in my system’ so I put a full recovery on my scans so they couldent get in. that fixed my problem.

  24. January 31, 2005 by Bobby Snow

    OUR computer keeps bloking us from letting us surf the web I’m thinking that it was a viruse. But, it wase’nt I lauched 4 programs at different times and the resolts all came out different, so I thought that there was virisius getting through the recoverd ‘holes in my system’ so I put a full recovery on my scans so they couldent get in. that fixed my problem.

  25. October 24, 2005 by Ilya Shustin

    I have a question rather than a comment. Running flash intensive application in Firefox causes the following issue: Opening a development page containing alot of flash as well as an embeded WMP. Close firefox and then try to open a new FF browser window. Checking in Task manager and Firefox is still running as a process. I attempted to open another firefox window and I get prompted wo choose another user profile because the current one is already being used. I see this as a major problem but not sure how to get around it. Any ideas??????

  26. Hi,

    I just found your site. There is a lot of good info. I am sure this is going to be a basic question for you, but I am new to browser incompatability problems. I am building a site and on the pages I am using a form with a textarea to display text which visitors can scroll. It works well, but just one problem. The form spacing is different in I.E. than Firefox. In Firefox it is aligned with the picture to the left. In Explorer it’s not. The box is too short. This is very frustrating and I know it is a spacing problem. But don’t know how I can resolve it. Can you help me, or at least point me to a good reference? Thanks for your time. James

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