Server Crashes from time to time

[Tezou]

Hello Community,

 

I made a new Hexxit server yesterday and was playing with some friends on it since then.

Everything works fine, no lagg, no delays or anything like this.

But it just crashes sometimes and I have no clue why.

I gave the server 6GB RAM, which should be enough, we are just four players.

That's the latest crash report: http://pastebin.com/tTs7RSj9

Plugins I have installed:

 

It's a 24/7 Server so I want it super stable.

 

I hope someone here can help me.

 

Greetings

Tezou