There's a similar thread here: http://support.mozilla.com/bs/questions/795314

I have found some what of a fix. I went into about:config and set gfx.direct2d.disable to true and arial black showed back up in FF using that font right now. Also forgot to say Im using the 64 bit 10.0a1 nightly release

You need to add font-weight:900 to make Firefox use Arial Black

• bug 644385 – Arial Narrow, Arial Black fonts do not show on page (comment 8)

I realize I have to add font-weight... but this is not a solution and they continue not to properly fix it. There have been several generations of Firefox with this bug now, without a fix... almost ready to leave for Chrome.

The problem is that in Window 7 the Arial fonts are placed in one Arial font group and you need extra selectors to select a specific member in that group or Firefox chooses the first member in that group. The same happens for other fonts that are placed in their own group.

Interesting, but Firefox still has that bug then and have neglected to update their broken code. More and more typography houses are doing what you describe because of the nature of opentype. Will Firefox ignore them as well? Still not a solution and wish FF would solve it.

I did not need to add font weight or anything to make arial black show up. It showed up when I set gfx.direct2d.disable to true. I did not add any font weight or anything else. And I over ride web fonts and use my own fonts in web pages and I am using arial black and have not set font weight to 900

eman17j: I think your solution is fine for you but I cannot give these instructions to everyone that views a site that my company creates. This remains a bug in FF that they are unwilling to fix.

quit using arial black then

You can always make a new @font-face property. Try font-squirrel and upload arial black. It will add about 50k of weight to your page though and isn't the best workaround.