Sporadically it happens that administration console is just "gone":
It happened two times in the past day that on http://localhost:4848 the following text is shown:
GlassFish Server 3.1
Your server is now running
To replace this page, overwrite the file index.html in the document root folder of this server. The document root folder for this server is the docroot subdirectory of this server's domain directory.
To manage a server on the local host with the default administration port, go to the Administration Console.
The funny thing is that the the word "Administration Console" actually is a link to http://localhost:4848, so clicking on it shows exactly the same page again.
The server.log does not tell anything about this strange circumstances: Only the usual message are contained that the console was started.