sign out/in to make admin work

Unless I explicitly sign out, and then sign right back in, many functions in the admin interface don’t work properly.

I used to be set up so that I would be brought right in to the admin screen (“remember me”) and that initially made me realize the problem. Now I have turned off “remember me” and have to enter a username/password to enter my admin, but the same problems persist unless I then logout and back in again.

This is what happens if I don’t logout/login:
– the preview writing window says “Not Found” when trying to write a post, unless I logout/login.
– adding categories and users simply doesn’t work
– the “add link” popup while writing a post pops up but is empty and while not allow itself to be closed unless you leave the page
– the upload interface doesn’t function properly
– and many other AJAX interface features are dead

Anyone have any thoughts? It’s extremely annoying to login, logout, and login again. I use FireFox 2.0.0.3 on Mac OS 10.4.9.