Since updating to Leopard on my Mac, the Cow is not automatically logging me in on FireFox or Safari.
Sometimes my name will be in the Post box. Sometimes nothing will be in the Post box. But my email Address is always missing the first time I try to respond to a post. after the first time it will stay logged in until i quit my browser.
I've made an adjustment to the auto-login that should make it work a little more consistently. Be aware that the function I believe you are referring to will only work if you only have one account per ip address as the auto-login feature is ip based.
Let me know if this adjustment has solved the problem as it's hard for me to test with multiple COW accounts associated with my ip address.