This from a long-time reader:
John, are you sure your blog is working properly? I think I have set up three accounts now, which have allowed me to post once per each of those accounts, then disallowed my password the next time I wanted to post. I've noticed that you are getting very few comments, which really surprises me, thus my suspicion that something is not right with the blog. I could be totally wrong about this and it may be that I just don't know what I'm doing (high probability) but maybe you should look into it. DennyAs far as I know, the guys at Google who run blogger (beta) know what they are doing. Lord know they have enough people and money to keep it maintained. My assumption is a problem like this would have been reported and resolved since it would affect a few bazillion blogs. I could not find anything in the help section or FAQ's about this.
My guess - and I stress the word "guess" here - is your browser security settings may be part of the issue. If the blog cannot read from your computer who you are it cannot link you to a stored account.
I'll keep investigating, but frankly I have discovered some these problems kinda go away as newer versions of browsers/blogger software are installed. Anybody who can help us out here would be eligible for a Major Award.
Another thought - you might try upgrading to Firefox 2.0 or IE 7.0
May the Force Be With You.