Wen says bad request the server isn't offline, you can change it in server.properties.
bad
400 Bad Request
It simply means the web server was unable to understand the request of the client and process it.
Please find below an article I have written on my blog to solve that issue: "How to Fix the "400 Bad Request" error message from a website" http://wp.me/p2519N-cB
Bad RequestYour browser sent a request that this server could not understand.newdiv
Bad RequestYour browser sent a request that this server could not understand.newdiv
Bad RequestYour browser sent a request that this server could not understand.newdiv
Bad RequestYour browser sent a request that this server could not understand.newdiv
Bad RequestYour browser sent a request that this server could not understand.newdiv
None to my knowledge - it would be bad business and bad for his or her image for an artists to request their fans leave their concerts.
Crappy internet, bad flashplayer, the server crashed for you. Google it and get more info on it.