My creative server has been crashing every few weeks but they all seem to share one thing in common, I see mention of NBT Tags but I can't work out what's actually causing the crash to take place and how to prevent it from happening.

Here are some examples of crashes I've been receiving:

1. http://pastebin.com/ptmr3QjG
2. http://pastebin.com/smaz825Y
3. http://pastebin.com/JbRG5wHu
4. http://pastebin.com/wRmGEaaf

I'm using this plugin which can be found on the Spigot resource page: https://www.spigotmc.org/resources/creativeitemcontrol.9471/ which consists of these features:

_Blocks access to items not in creative menus.
Selectively block access to specific creative menus.
Blocks hacked clients from spawning op me books.
Blocks hacked clients from spawning command blocks.
Blocks hacked clients from spawning items with custom NBT.
Does not block crafted or enchanted items not available in menus unless explicitly blacklisted.
Selectively block access to specific items.
Custom permission messages.
Custom broadcast messages and targets.
Custom commands on violations, automatically kick or ban.
Ability to broadcast full item NBT so you can see exactly what was blocked.
Whitelist to allow custom NBT on some items._

But even with all this, I'm still having the same type of crashes which is very annoying to deal with because I usually have around 500 players connected on the server, any help would be much appreciated.