How do I fix Yahoo Mail Unicode icons failing to load?

I'm running Firefox 25 on a Windows 7 Home system, and the none of the new unicode icons that Y! mail uses are loading (I'm getting the unicode squares with the code). What do I need to do to fix this? I've tried clearing my browser cache, restarting my browser, restarting my computer. The icons work on this system using IE, but the performance degradation of having to use IE kills me (as in it literally takes 20 minutes to open IE and load Y! mail). Is there a unicode add-on pack for FF25 I can download and fix it? As a side note, the icons do load on my FF25 Windows Vista laptop, so I know it is not FF25 specifically, just my installation on this system.