There are some reports of Google Webmaster Tools not loading for some users. Some of these reports are coming from WebmasterWorld and I also personally have this issue.

When I try to access the tool, the URL redirects back and forth between the Google Account authentication system and the webmaster tools home page. If I try a different browser, it lets me in, so it seems to be a cookie issue for some users.

Firefox Error:

Safari Error:

I can login to all other Google properties without an issue, I am just having this issue with Google Webmaster Tools. I rather not delete my Google cookies, cause that will stop them from tracking me for the past 15 years. 🙂

Forum discussion at WebmasterWorld.