Using Firefox, Safari, or Chrome, I navigate to the Sitefinity login screen. After logging in, I'm redirected to a page that says that "There were too many redirects." Firefox navigates to a page that claims "The page isn't redirecting properly." To access Sitefinity, I have to remove everything after the word "Sitefinity" in the URL bar. If someone else is logged in to Sitefinity, it is not possible to log them out and access Sitefinity via Chrome or Safari. The "Too many redirects" page comes up no matter what. Clearing cookies, cache, and plug in data does not resolve the issue. Another Sitefinity forum post suggested to specify a UTF-8 charset, which didn't help, even after restarting the Sitefinity application. Chrome specifies this problem as "Error 310 (net::ERR_TOO_MANY_REDIRECTS)."
This does not happen when logging in via the actual site, e.g. www.example.com/sitefinity. Only on the local and preview versions that allows the customer to see the site, e.g. http://server/example/sitefinity and preview.websitecompany.com/example/sitefinity.