black king does not display with Firefox

On newer versions of Firefox, the black king on online chess does not display. I've tried it on several different machines--Mac 10.5 and Windows XP--and have tried disabling and uninstalling any adblocking software, but still no black king. On a Mac, I have this problem with Safari, too (I haven't tested other browsers on a PC). 

Anyone else experience this problem, or is it just me?

Update: Same problem w/ FF 3.6.12 in Windows XP.

screenshot of online chess with FF 3.6.8 on an Intel Mac running OS 10.5.8:

I am running FF 3.6.12 on the exact same OS and I have no problem.

"Float like a butterfly, sting like a bee. You can't checkmate what you can't see." 

Anyway, I got firefox and the black king shows up just fine. 

I run FF 3.6.8 on a PPC Mac OS 10.4 at home and have no problem.