Looks like Google has changed how you can use it's Keyword Suggestion Tool. I used to be able to use the external tool without being signed in by simply filling out the captcha.
Now however you are taken to a sign-up page:
After entering the captcha you are taken to a sign-up wizard to compete your campaign:
Looks like Google is pushing people to sign up for ad-words and/or activate their adwords accounts. This change comes one year from the rollout of the new keyword tool. Google began offering the keyword took in September 2009