Font - awesome fonts that can be problematic with IE11

We have been using Font-Awesome 4.0.2 and have been doing it for about 18 months. Most recently, with IE 11.0.9600 17843, we noticed intermittent rendering issues. We can CTRL-F5 and the fonts will appear, then go to the page and go back and find some fonts. When you hover over them, they reappear.

In some cases of the same IE11 browser (64-bit not 32-bit) it works fine. We have checked the security settings, i.e. fonts can be downloaded.

No problem with Mozilla or Chrome.

Oddly enough, the problem exists with the live site, not the QA site. Both are on the Internet.

I researched this and the intermittent nature is the key and it could indicate a bug in the recent IE11 update, as it did work with IE11.

The council appreciated ...

Should we update to the newest Font-Awesome, which is 4.3, or does this new version contain more fonts?

Thanks in advance.