Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Go to Firefox > History > Clear recent history or (if no Firefox button is shown) go to Tools > Clear recent history.
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the Clear now button.

Further information can be found in the Clear your cache, history and other personal information in Firefox article.

Did this fix your problems? Please report back to us!

Hi Richard52, when you posted, your browser identified itself as Firefox 19, but in your question you mentioned Firefox 17. Is that on a different computer? If so, and it's not the corporate ESR version, you probably want to update that one to Firefox 19 as well to get all the latest security patches.

Edit: For what it's worth, I run WordPress 3.5.1 on my own server and haven't noticed anything strange in the dashboard in Firefox 19.0.2.

Hi feer56 and jscher2000,

I'm experiencing problems seeing the Visual Editor of Wordpress (my own domain, not wordpress.com) only in Firefox. I'm pretty sure it's not a Wordpress problem (Opera and Chrome show it OK).

The visual editor is part of the Dashboard of Wordpress. Other aspects of dashboard in Wordpress is OK.

I'm running Wordpress 3.5.1, Ubuntu 13.04 and Firefox 21.0, always updated all of them.

I tried the above solution, clearing cookies and cache, and it didn't work out.

I'm wondering if it's a Javascript problem... because other browsers render OK the same page with visual editor. Only my dearest Firefox is having this issue.

How can I troubleshoot this issue in order to fix it? Please help.

Hi celiapgt, I'm familiar with the post editor, is this the same thing? If it's something different, can you describe the steps to take to get into the area where you see the problem.

I just realize I don't have the Visual vs. HTML tabs either. I discovered the cause in my case:

Users > Your Profile > "Disable the visual editor when writing"

Not sure why that was turned on, maybe it was to improve the performance of the page (I am used to seeing HTML tags).

Could you double-check that setting?

If that isn't it, another common suggestion is to try disabling various plugins on the theory that one of them might conflict.

From the Firefox side, could you try Firefox's Safe Mode? That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled

In the dialog, click "Start in Safe Mode" (not Reset)

Any change?

Safe mode does not automatically disable plugins. If you want to rule those out as well, you can disable them here:

orange Firefox button (or Tools menu) > Add-ons > Plugins category

Hi, jscher2000:

Thanks for answering so soon!

I double checked and I don't have disabled the Visual Editor in my user's preferences. With this hint on mind, I checked and uncked again to see any chnges. None. I logged out as my user and logged in as another user (with privileges to edit, of course). No change, whatsoever.

Yes, I had restarted without any extensions nor themes (manually disabled), and in safe mode. In both cases I get the same: no Visual+HTML tabs in post editor in Wordpress. I doubled-checked ans I have visual editor in Opera and Chrome.

I checked with WebDev tool, and see some -moz-* rules errors in the log. Some rules were dropped while loading the page. Could it be that some CSS3 rules are not being processed, like the width of the tabs? I'm guessing...

Hi celiapgt, I'm only able to test on Windows, where it is working fine. I can't think of any Linux-specific issues that would disable the editor.

Do you have any WordPress plugins that change the editor in any way? Maybe one of those isn't fully Firefox compatible.

Well, jscher2000, I'm confused. In my Toshiba laptop, Firefox is OK with visual editor (I run Ubuntu as well), but in my HP desktop, no. Anyway, as you say, editing with HTML is good enough for me...

As we say in México, it's a mistery for the spider, ;-)

Thanks for your interest and help. Maybe it will solve by itself in the future. Of course, if I glimpse the cause, I'll let you know.