My server keeps crashing due to the fact that when you join, you have a 50.2% chance of having it say: Timed Out, or a 50.8% chance of showing the world, but no chunks loaded.

I do not know whats wrong, but I caught a crash report. I copied and pasted, so the lines may not be 100% accurate.

---- Minecraft Crash Report ----
// Uh... Did I do that?

Time: 2/29/16 8:02 PM
Description: Watching Server

java.lang.Error
at java.util.concurrent.ConcurrentHashMap.remove(Unknown Source)
at java.util.Collections$SetFromMap.remove(Unknown Source)
at lo.b(SourceFile:66)
at lo.c(SourceFile:73)
at lo.d(SourceFile:91)
at aht.a(SourceFile:297)
at aht.f(SourceFile:293)
at aht.o(SourceFile:674)
at rr.ac(SourceFile:818)
at rr.d(SourceFile:759)
at sa.g(SourceFile:1499)
at sa.n(SourceFile:1782)
at sb.n(SourceFile:488)
at sa.m(SourceFile:1615)
at sb.m(SourceFile:276)
at yx.m(SourceFile:123)
at aht.a(SourceFile:1515)
at lp.a(SourceFile:719)
at aht.g(SourceFile:1493)
at aht.k(SourceFile:1383)
at lp.k(SourceFile:552)
at net.minecraft.server.MinecraftServer.D(SourceFile:625)
at la.D(SourceFile:339)
at net.minecraft.server.MinecraftServer.C(SourceFile:553)
at net.minecraft.server.MinecraftServer.run(SourceFile:457)
at java.lang.Thread.run(Unknown Source)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at java.util.concurrent.ConcurrentHashMap.remove(Unknown Source)
at java.util.Collections$SetFromMap.remove(Unknown Source)
at lo.b(SourceFile:66)
at lo.c(SourceFile:73)
at lo.d(SourceFile:91)
at aht.a(SourceFile:297)
at aht.f(SourceFile:293)
at aht.o(SourceFile:674)
at rr.ac(SourceFile:818)
at rr.d(SourceFile:759)
at sa.g(SourceFile:1499)
at sa.n(SourceFile:1782)
at sb.n(SourceFile:488)
at sa.m(SourceFile:1615)
at sb.m(SourceFile:276)
at yx.m(SourceFile:123)
at aht.a(SourceFile:1515)
at lp.a(SourceFile:719)
at aht.g(SourceFile:1493)
at aht.k(SourceFile:1383)
at lp.k(SourceFile:552)
at net.minecraft.server.MinecraftServer.D(SourceFile:625)
at la.D(SourceFile:339)
at net.minecraft.server.MinecraftServer.C(SourceFile:553)

– Thread Dump –
Details:
Threads: "Netty Server IO #3" Id=21 RUNNABLE (in native)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source)

• locked io.netty.channel.nio.SelectedSelectionKeySet@4628edd3
• locked java.util.Collections$UnmodifiableSet@48ef1b66
• locked sun.nio.ch.WindowsSelectorImpl@4cd086a3
  at sun.nio.ch.SelectorImpl.select(Unknown Source)
  at io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:622)
  at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:310)
  ...

"Netty Server IO #2" Id=20 RUNNABLE (in native)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source)

• locked io.netty.channel.nio.SelectedSelectionKeySet@9d2115d
• locked java.util.Collections$UnmodifiableSet@89533c1
• locked sun.nio.ch.WindowsSelectorImpl@38113d9e
  at sun.nio.ch.SelectorImpl.select(Unknown Source)
  at io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:622)
  at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:310)
  ...

"Netty Server IO #1" Id=19 RUNNABLE (in native)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source)

• locked io.netty.channel.nio.SelectedSelectionKeySet@70bc41a1
• locked java.util.Collections$UnmodifiableSet@69fdee12
• locked sun.nio.ch.WindowsSelectorImpl@48d7d3d7
  at sun.nio.ch.SelectorImpl.select(Unknown Source)
  at io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:622)
  at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:310)
  ...

"Java2D Disposer" Id=24 WAITING on java.lang.ref.ReferenceQueue$Lock@799bea9e
at java.lang.Object.wait(Native Method)

• waiting on java.lang.ref.ReferenceQueue$Lock@799bea9e
  at java.lang.ref.ReferenceQueue.remove(Unknown Source)
  at java.lang.ref.ReferenceQueue.remove(Unknown Source)
  at sun.java2d.Disposer.run(Unknown Source)
  at java.lang.Thread.run(Unknown Source)

"Server Watchdog" Id=23 RUNNABLE
at sun.management.ThreadImpl.dumpThreads0(Native Method)
at sun.management.ThreadImpl.dumpAllThreads(Unknown Source)
at lb.run(SourceFile:43)
at java.lang.Thread.run(Unknown Source)

"Netty Server IO #0" Id=18 RUNNABLE (in native)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source)

• locked io.netty.channel.nio.SelectedSelectionKeySet@6bb80d45
• locked java.util.Collections$UnmodifiableSet@6db3f35e
• locked sun.nio.ch.WindowsSelectorImpl@1b0ccc54
  at sun.nio.ch.SelectorImpl.select(Unknown Source)
  at io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:622)
  at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:310)
  ...

"Server console handler" Id=16 RUNNABLE (in native)
at java.io.FileInputStream.readBytes(Native Method)
at java.io.FileInputStream.read(Unknown Source)
at java.io.BufferedInputStream.read1(Unknown Source)
at java.io.BufferedInputStream.read(Unknown Source)

• locked java.io.BufferedInputStream@3de51ab1
  at sun.nio.cs.StreamDecoder.readBytes(Unknown Source)
  at sun.nio.cs.StreamDecoder.implRead(Unknown Source)
  at sun.nio.cs.StreamDecoder.read(Unknown Source)
• locked java.io.InputStreamReader@169cea6d
  at java.io.InputStreamReader.read(Unknown Source)
  ...

"DestroyJavaVM" Id=15 RUNNABLE

"Server thread" Id=13 RUNNABLE
at java.util.concurrent.ConcurrentHashMap.remove(Unknown Source)
at java.util.Collections$SetFromMap.remove(Unknown Source)
at lo.b(SourceFile:66)
at lo.c(SourceFile:73)
at lo.d(SourceFile:91)
at aht.a(SourceFile:297)
at aht.f(SourceFile:293)
at aht.o(SourceFile:674)
...

"Server Infinisleeper" Id=12 TIMED_WAITING
at java.lang.Thread.sleep(Native Method)
at la$1.run(SourceFile:77)

"Snooper Timer" Id=11 WAITING on java.util.TaskQueue@64c7d2e3
at java.lang.Object.wait(Native Method)

• waiting on java.util.TaskQueue@64c7d2e3
  at java.lang.Object.wait(Unknown Source)
  at java.util.TimerThread.mainLoop(Unknown Source)
  at java.util.TimerThread.run(Unknown Source)

"Attach Listener" Id=5 RUNNABLE

"Signal Dispatcher" Id=4 RUNNABLE

"Finalizer" Id=3 WAITING on java.lang.ref.ReferenceQueue$Lock@19d4cc43
at java.lang.Object.wait(Native Method)

• waiting on java.lang.ref.ReferenceQueue$Lock@19d4cc43
  at java.lang.ref.ReferenceQueue.remove(Unknown Source)
  at java.lang.ref.ReferenceQueue.remove(Unknown Source)
  at java.lang.ref.Finalizer$FinalizerThread.run(Unknown Source)

"Reference Handler" Id=2 WAITING on java.lang.ref.Reference$Lock@cf17d5a
at java.lang.Object.wait(Native Method)

• waiting on java.lang.ref.Reference$Lock@cf17d5a
  at java.lang.Object.wait(Unknown Source)
  at java.lang.ref.Reference$ReferenceHandler.run(Unknown Source)

Stacktrace:
at lb.run(SourceFile:59)
at java.lang.Thread.run(Unknown Source)

– System Details –
Details:
Minecraft Version: 1.9
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_40, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 399377728 bytes (380 MB) / 533200896 bytes (508 MB) up to 954728448 bytes (910 MB)
JVM Flags: 3 total; -Xms256M -Xmx1024M -XX:MaxPermSize=64M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Profiler Position: N/A (disabled)
Player Count: 0 / 60; []
Is Modded: Unknown (can't tell)
Type: Dedicated Server (map_server.txt)

Sorry I couldn't do a console one, but it says the UUID and player stuff like that is loaded. Also the ticks is being skipped a lot.