I am trying to create an alert, and when I get to the Trigger Conditions section, I am unable to select anything in any of the conditions. There is nothing in the first drop-down box:

I suspect something is not populating. I have tried copying existing Alerts, as well as creating brand new ones. The behavior is the same, across all browsers. My other admins get the same result on their machines as well.
Wha hoppend?
-Paul