The most common reason for this problem is you are not logged in. Some of our pages are visible to logged-out members but do not allow you to access the content within those pages. If you view or click the login link and confirm that you are logged in, this should solve the problem.
A second reason this problem occurs is that your account has expired and your access can only be returned by re-enrolling in the membership.
A third reason this problem may occur is with brand new classes that are added to the site and sometimes there may be permissions that need to be set up, but this would only apply to a newly created class or group, but in this case you would still be able to access your prior class and group areas.