[SEVERE] java.io.IOException: Server returned HTTP response code: 500

Why do people get this error, they cant join the server and how do i fix this?
Using latest CB build.
Plugins:
BorderGuard, ColorMe, CreeperHeal, HeroicDeath, iConomy
, Minequery, MonsterBox, NoCheat, noEnderman, ServerSave, Permissions, Votifier,
WorldEdit, dynmap, AdminCmd, ChestShop, Factions, PermissionsBukkit, Register
Error in console:
2011-10-07 19:53:21 [SEVERE] java.io.IOException: Server returned HTTP response code: 500 for URL: http://session.minecraft.net/game/checkserver.jsp?user=DES_Jake&serverId=5261d48d18cbd1c2
2011-10-07 19:53:21 [SEVERE] at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
2011-10-07 19:53:21 [SEVERE] at java.net.URL.openStream(Unknown Source)
2011-10-07 19:53:21 [SEVERE] at net.minecraft.server.ThreadLoginVerifier.run(ThreadLoginVerifier.java:34)
2011-10-07 19:53:21 [INFO] DES_Jake [/90.204.81.100:2586] lost connection

 

The minecraft.net servers are down at the moment.

 

Thank god

 

they can join if they try it multiple times

 

@Switch0r Just so you know, all the people on this thread are having the same issues.

@strontkever The servers's are up and down continually. Some players may manage to get in, yes, but the issue is still there and many players won't be able to get on at all.