Try to set the gfx.content.azure.enabled pref to false or if this didn't help disable Direct2D by setting the gfx.direct2d.disabled pref to true on the about:config page and leave hardware acceleration otherwise enabled. That way you still have the benefit from hardware acceleration, but may not suffer from rendering issues.

You can also try to uninstall Windows update KB2670838 if you have this update.

• http://support.microsoft.com/kb/2670838

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I figured it was an update because I did not have this prob until later updates but did not want to confuse the issue, uninstalling KB2670838 seems to have done the trick, Thanks so much guys, I love my firefox!

I greatly appreciate the tips listed here. I would like to add my experiences so far. I am suffering from this exact problem as well. Firefox 24 and 24b10 both have the problem, and only since I upgraded to Windows 8.1. A full uninstall and reinstall of Firefox and clean profile troubleshooting does not help. I have noticed something, however, I think. This issue seems to only occur with Sans Serif or Serif type? MAYBE Times New Roman as well. I am still working on figuring this one out, but the reason I mention this is that the issue is especially noticable when posting in forum boxes where the default font used in Sans Serif. Anyone else?

J'apprécie beaucoup les conseils énumérés ici. Je voudrais ajouter mes expériences jusqu'ici. Je souffre de ce problème exact aussi. Firefox 24 et 24b10 ont tous deux le problème, et que depuis je suis passé à Windows 8.1. Un plein désinstaller et réinstaller de Firefox et profil propre dépannage n'aide pas. J'ai remarqué quelque chose, cependant, je pense. Ce problème semble se produire qu'avec Sans Serif ou le type Serif? PEUT-ÊTRE Times New Roman ainsi. Je travaille toujours sur de trouver celui-ci, mais la raison pour laquelle j'en parle, c'est que la question est d'autant plus perceptible lors de la publication dans des boîtes de forum où la police par défaut utilisée dans Sans Serif. Quelqu'un d'autre?

Edited to add Google translation to French.

Hi WickedGirl, your Windows 8.1 update may have included an update related to IE10 that you hadn't installed before.

There was a problematic update this past Spring which affected fonts in Firefox. That is discussed in this thread: Workaround for font issues caused by IE10 update. I don't know whether Microsoft has changed that by now, but perhaps not.

Hi WickedGirl, also, the release numbering system may not be obvious, but the "b" indicates a pre-release beta version, so 24.0b10 is prior to the final 24.0 release.

jscher2000...Thank you SO much for the info. I love it when people take the time to give me tidbits of info that I need. My Windows 8 was up to date completely before I installed 8.1 (at least according to Windows Update). However, you can bet I am going to read that link you sent to me. I have often found that if something is a recurring problem, even if it was fixed years ago just two weeks ago, one should never overlook any information on that issue if the same symptoms apply. I have worked with all kinds of software over the years, and programmers can and do easily overlook something and allow a problem right back into a program. Your link is going to be one more step in my knowledge search for this annoying issue!  :)

And yes, I experimented with the Firefox versions because I was wondering if the problems would be found in the same version number but perhaps left out in one of the same version's betas. No such luck. I wonder if I downgrade to 23 if the problem would still be there. And how does this relate to Azure? I am going to have to read up on Azure and it seems dry. Ack! I hate dry tech stuff. I am better with plain speech for my tech. Too impatient to know why something is happening.

By the way, some posts suggest uninstalling IE 10 to fix this problem. What specifically would uninstalling another browser do for Firefox? And, last I read anything about it, you cannot uninstall Internet Explorer from Windows? Has that changed in Windows 8?

Hi WickedGirl, I think uninstalling IE 10 would be an option for those whose system was delivered with IE 9, so it would cause Windows to roll back to IE 9. If Windows 8 comes with IE 10, then you're right that you cannot uninstall it, and you wouldn't want to because some sites require support for ActiveX controls.

I haven't studied the details of why the IE 10 font-related changes affect Firefox. Hopefully that is covered in the other links.

I suppose you could be correct about uninstalling IE10 reverting to IE 9. I never tried before. <rolls eyes thinking about all the current Windows 8.1 issues she is experiencing and reverting backwards in any way if possible>

I am actually a Windows 8 LOVER, but I am currently a highly annoyed Windows 8.1 hater. I wish I had not upgraded yet.