Minecraft server stops when some players quit

my OS is CentOS
architecture is x86
and for the version of java I have more then one version installed, when i do the command java -version it shows a old version. the 3 version i have installed are:
jdk1.5.0_22 -- this is what shows when i do java -version
jre1.6.0_24 -- This is the version my CB is running on
tomcat5.5 -- This i dont know.
I do not use any wrappers
I am using CB 766

The command i use to start my CB is

Plugins: Permissions, Essentials, EssentialsSpawn, EssentialsChat, Residence, craftbukkituptodate, heroic death, whitelist, Autosave, minequery, No cheat, Simple Log

Server Log Where the problem is:

The problem is that randomly my minecraft server will just turn off with out any warning, when a player quits it has happened a few times and its starting to get annoying. I have no idea whats causing this problem. My server has 2 gb of ram and this has only started after i updated bukkit to 740 and it still is going on now that its at 766. This might be a bug can someone help me out here, i want to make sure that this stops happening.

 

Would they happen to be an op on the server? If so, they can just use the /stop command.

 

no its normaly only normal users on no ops, it has happend once when i logged out and im the only op