Problem DW20 1.0.12 Exception Ticking World Crash

[MathMusic]

Recently, my dedicated local server has been crashing and throwing an Exception Ticking world crash whenever players try to log in or return to the overworld from the Nether. Most recently, it has started crashing even before players log in.

Server log: http://pastebin.com/18BJP1PG
Crash Logs: http://pastebin.com/sE3bb3jE , http://pastebin.com/i2hyyj2V

I am running a Windows 7 machine, Java 7 u 51 (64 bit), with 16 GB RAM (8GB allocated to Minecraft). No additional mods were installed.

Any help would be appreciated.

 

[Wagon153]

Not sure if this is related, but a chunk is in the wrong spot according to the console log.

 

[MathMusic]

For some reason, resetting the nether has appeared to resolve this issue. I'm thinking that an ender-thermic pump was causing this issue.