I have had a problem with a personal WordPress blog I installed a long time ago but never got the chance to look into until recently which is the fact that the logon part of the site was not auto logging me on. Not only was the blog not auto logging me on but it was not remembering my password though it would remember my username. This blog has been around since before WordPress 2.5 and I have upgraded from time to time. I remember the issue started somewhere around the time that I upgraded from WordPress 2.5 to WordPress 2.6 so that is where I started the troubleshooting process and sure enough I was able to find the answer pretty easily. I had been in a rush when upgrading the site and once I had time to go back and read the documentation I found some configuration file options located in wp-config.php that had been added with WordPress 2.6. There were 3 security key configuration options added in WordPress 2.6 and fourth security key added in WordPress 2.7.