I was just visiting feedburner and much to my shock almost all my sites said that they had zero subscribers!
Obviously something strange has happened at feedburner or at least I kind of hope that something has. I mean, some of my sites have a few hundred subscribers or they did up until I checked my feedburner stats a few minutes ago.
Check your feedburner account and see if your subscribers have suddenly decreased or worse fallen to zero.
Let me know what you find out?