ConcurrentModificationException Error?

I keep getting this error on my server and I have no idea what it means.
I have about 20 plugins on my server and all of them start up clean with no errors.
The console is also clean with no errors while the server is running.

This error happens over 20 times a day and it freezes my server forcing me to restart.
I cant save it ingame when this happens, but if i log onto the console through putty quick enough it can save it. I am using brohoster as my server host.





My plugins on the server.



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

 

Had a error like that once.. A bukkit update made it go away. I'm no java expert but it looks like something is trying to clear entities, now I know Towny does that, but since you don't have that, could it be regios? Might trying to disable that plugin for a bit and see how the server runs.

 

I removed 3 plugins (chest absorb, online users, and showcase.)

It seems the problem is fixed.