My server needs help!

I don't know if it is my computers problem or my server's but there has been a very weird problem happening to my server. Since yesterday, everyone who joins my server (including me) keeps on disconnecting after a second they join. I don't know what this problem is but to help you guys i will include the server log in the link below.
http://pastebin.com/UkigECj1

Info you might need to know:

Server ip: constructioncraft.servegame.com
server port: 25565
ram: 3
Plugins: Essentials, Clearlag, Groupmanager, Multiverse- core, Playerheads, Plotme, PluginMetrics, SimpleAutoAnnouncer, Updater, WorldEdit, WorldGuard

This is a craftbukkit server.