This bug seems to be triggered when your browsing session has been inactive for a while, and you click on New Posts. Rather than taking you to the login page (or maybe it tried to), it sends two Location: headers which are for redirection. Chrome interprets this as an attack attempt and gives the message below.
The workaround is to go to the home page forums.opensuse.org and login in again. It's not seen very often and probably only on Chrome, which is getting very careful.Duplicate headers received from server
The response from the server contained duplicate headers. This problem is generally the result of a misconfigured website or proxy. Only the website or proxy administrator can fix this issue.
Error 350 (net::ERR_RESPONSE_HEADERS_MULTIPLE_LOCATION): Multiple Location headers received. This is disallowed to protect against HTTP response splitting attacks.