(adsbygoogle = window.adsbygoogle || []).push({}); ok so i run the jar file and this is what it does, could somebody help please

    [info] starting minecraft server version beta 1.6.6

[info] loading properties

[info]starting minecraft server on *:25565

[severe] Unexpected exception

java.lang.NoSuchMethodError: method

java.net.serversockect.setperformancepreferences with signature (III)v was not 

found.

  at cs.<init>(sourcefile:29)

  at net.minecraft.server.Minecraftserver.c(sourcefile:130)

  at net.minecraft.server.minecraftserver.rin(sourcefile:284)

  at bo.run(sourcefile:422)