WTF, Yahell?

So, I attempted to log in to Yahoo Groups, using the shared computer at my workplace. The sign-in surface is different from the one I'm used to: instead of the username and the codeword, it asks for my e-mail address. I use different e-mail addresses to my various groups. Yahoo refuses to recognize either of them. Result: I can't log in. Any ideas why this is happening and how could we get around it?