Login problems after upgrading to 2.6.1; blog not displaying either!

After upgrading to WP 2.6.1 from 2.6 using WP Automatic Upgrade, my blog keeps on prompting me to login every few minutes. I cleared my cache and cookies, but the problem persists. I’m using Firefox 3. I also changed the secret key (API 1.1 version), just in case. Still the problem remains. Also, sometimes during re-login it gives an ‘Incorrect username’ error, when it most definitely isn’t (I store it in Firefox’s password manager). Clicking the login button immediately after that still allows me to login, and allows me to use the admin interface for a while before asking to login again.

Also, check my blog – ankurb.info – no posts are showing up! It gives an error. Plus, even if I get to the create new page, I can’t post anything because it keeps taking me back to the login page. If I do make it to the ‘Post New’ page, then after a while when the auto-save kicks in, it gives an error saying ‘You don’t have the permission to do that’ at the place where the save status of a post generally shows up.