Yes this extension has been very problematic of late, seems to work for some people and not for others, can't say why this would be. I keep promising to remove this extension as my time is spent developing my skin, nevertheless lets try and resolve this for you.
If you open font-awesome.css there should be some links at the top, these link to the fonts (in the font folder) have a play with those, I did test this previously because one of my developers screwed around with the links and didn't put them back before uploading, but I thought I'd solved this problem.
If you're worried about showing a link here, you can email me - info[at]mediawikibootstrapskin.co.uk will make solving this problem a whole lot easier if I can take a look.
You might consider using the skin btw, it includes font-awesome, glythicons and fam-fam icons - see here.