Server times out, generates a crash report yet still says online.

This has been going on for over a month now. At random times (mostly when im asleep lol) my server crashes with this:

2013-01-07 10:23:02 [SEVERE] Encountered an unexpected exception ReportedException
net.minecraft.server.v1_4_6.ReportedException: Exception ticking world entities
at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:584)
at net.minecraft.server.v1_4_6.DedicatedServer.r(DedicatedServer.java:224)
at net.minecraft.server.v1_4_6.MinecraftServer.q(MinecraftServer.java:494)
at net.minecraft.server.v1_4_6.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.v1_4_6.ThreadServerApplication.run(SourceFile:849)
Caused by: java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
at java.util.ArrayList$Itr.next(Unknown Source)
at net.minecraft.server.v1_4_6.World.tickEntities(World.java:1228)
at net.minecraft.server.v1_4_6.WorldServer.tickEntities(WorldServer.java:445)
at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:580)
... 4 more
2013-01-07 10:23:02 [SEVERE] This crash report has been saved to: /home/server14987/./crash-reports/crash-2013-01-07_10.23.02-server.txt

And here is the crash report on pastie:

http://pastie.org/5643649


Please help ^_^

Bump

EDIT by Moderator: merged posts, please use the edit button instead of double posting.