As a glance at the Kinja-Help tag indicates, a lot of people, if not everyone are having problems with comments this morning. I'm sure eventually they get them fixed and I'm having a little trouble understanding the rhyme or reason, but right now, it's frustrating to say the least.
They keep blinking in and out. I'm sure eventually they'll take hold.
FWIW: I'm having issues with Chrome, Firefox and IE on both Win7 and XP.