This official news post is copied verbatim from the RuneScape website. It is copyrighted by Jagex.
It was added on 7 September 2012.
It was added on 7 September 2012.
We're updating the signing certificate used to authenticate the applets used to run our games. The next time you log in, you'll be asked to accept this new certificate. This will only need to be done once - not each time you load the game.
Users of the downloadable RuneScape client will receive an error message when attempting to log in, until the latest version of the client is downloaded. You can find the latest version here.
The RuneScape Team