I attempted to log onto my VSA and it says "The challenge/response security mechanism timed out. Please log in again".
The log in page is very time dependent. The username/password and domain (if applicable) are hashed along with the time and sent to the server. The log in page does not auto refresh, which means that the time stamp it has, is the time that the page is loaded. If the log in attempt does not happen within a few seconds of the page loading, then the page will give this message.
If the time from the page loading, to the time that the log in happens drifts too far, then the authentication will fail.
This stops someone being able to re-use that session.
The solution is either to refresh the page and log in straight away, or log in immediately after loading the page.
This is a security measure and expected behavour.
VSA v7.0, v8.0