Internal Server Error

As I tried to log into my friends server, I got the error "Internal Server Error"

and this is that error that the server has put out:

2013-03-01 00:00:42 [INFO] Huntondoom/-...-:2298 logged in with entity id 143 at (35.147206481283284, 96.0, -111.30312880793065)
2013-03-01 00:00:43 [WARNING] Failed to handle packet for Huntondoom/--.--.--.--: u: Ticking player
u: Ticking player
at jb.g(SourceFile:209)
at jg.a(SourceFile:201)
at ed.a(SourceFile:136)
at ci.b(SourceFile:350)
at jg.d(SourceFile:59)
at jh.b(SourceFile:35)
at id.b(SourceFile:30)
at net.minecraft.server.MinecraftServer.r(SourceFile:480)
at hy.r(SourceFile:255)
at net.minecraft.server.MinecraftServer.q(SourceFile:397)
at net.minecraft.server.MinecraftServer.run(SourceFile:331)
at go.run(SourceFile:573)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 4
at sh.c(SourceFile:1544)
at nd.c(SourceFile:1246)
at sh.c(SourceFile:371)
at nd.l_(SourceFile:551)
at sh.l_(SourceFile:201)
at jb.g(SourceFile:178)
... 11 more
2013-03-01 00:00:51 [INFO] Huntondoom/-...-:2323 logged in with entity id 145 at (35.147206481283284, 96.0, -111.30312880793065)
2013-03-01 00:00:51 [WARNING] Failed to handle packet for Huntondoom/--.--.--.--: u: Ticking player
u: Ticking player
at jb.g(SourceFile:209)
at jg.a(SourceFile:201)
at ed.a(SourceFile:136)
at ci.b(SourceFile:350)
at jg.d(SourceFile:59)
at jh.b(SourceFile:35)
at id.b(SourceFile:30)
at net.minecraft.server.MinecraftServer.r(SourceFile:480)
at hy.r(SourceFile:255)
at net.minecraft.server.MinecraftServer.q(SourceFile:397)
at net.minecraft.server.MinecraftServer.run(SourceFile:331)
at go.run(SourceFile:573)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 4
at sh.c(SourceFile:1544)
at nd.c(SourceFile:1246)
at sh.c(SourceFile:371)
at nd.l_(SourceFile:551)
at sh.l_(SourceFile:201)
at jb.g(SourceFile:178)
... 11 more