At my first login to unix.stackexchange.com I noticed the following behaviour:
I came to the MySQL / swap space full page page from Google. As I noticed this to be a Stack Exchange site, I clicked ‘log in’ to vote up the question. After logging in with Stack Exchange OpenID provider, I got the question: Do you wish to share your information with unix.stackexchange.com? I said ‘Confirm’, but then I got redirected to the start page http://unix.stackexchange.com/, not back to the article as, IMHO, it should work.
The browser was Firefox 17.0.1.
The workaround is to go back using the browser history (you stay logged in then), but, IMHO, it’s a minor bug anyhow.