It's been 5 years, and this still isn't fixed. Reminds me of a company that has never admitted there might be a problem with its driveshafts.

Just read the articles in Dec. '09 Airmail by Jim Howland and David Cushing about membership and website issues so I'm here to see whether this problem has been fixed. It hasn't. Some pages (such as this one) are accessible, others aren't. I've tried various machines and browsers, turned off the firewall, cookies are enabled, etc. Today's experiment: while logged in I saved a bookmark to the Site Instructions page. Then I logged out, closed the browser and restarted it. I clicked the bookmark and got the 'Not Authorized' message, proving that that page is protected, not merely hidden, and is able to authenticate me when I'm logged in.