[INFO] NewlySpawnedPlayer fell out of the world

I've been having this problem for a while now. Almost every time a new person joins my server, they fall out of the world for no reason. They lose their kit/first spawn items, and lots of the time people leave because of it. I've done tons of things to fix it; nothing has worked. Here's some more info:
CraftBukkit Version: CraftBukkitt-1.4.7-R1.0
Plugins installed (As name of .jar file)
BeHerobrine1.5.1
ChatManager
clearlag
DisguiseCraft
EnjinMinecraftPlugin
Essentials
EssentialsSpawn
JCVaultListener-2.0.3
Lockette
MobArena
Multiverse-Core-2.5
Multiverse-Inventories-2.5
Multiverse-Portals-2.5
PermissionsEx
PlotMe
SignShop
Simple-AutoSave
SimpleRestart
VanishNoPacket
Vault
vAuth
Votifier
WorldEdit
WorldGuard
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I don't know what the problem is, if I had to guess I'd assume it has something to do with Essentials and/or vAuth. My server stays offline-mode, so I use vAuth to protect it. It's essential to my server. If I had to move to another authentication plugin, I wouldn't know what to do about passwords. They are saved in code, so there is no way I could simply migrate without risk. I no longer have any ideas. Please help!
P.S. No, I don't have cracked Minecraft. Yes, I have a premium account named PorkyFish14

 

No support for offline-mode servers is given on these forums.

 

Before staff closes this thread, I have feelings for Offline-Mode. Your problem is xAuth. Fill any blocks under your spawn point. There has to be atleast 5 blocks under spawn or the player will fall.

 

No support is provided for servers running in offline mode, due to how insecure it is. Good luck resolving the issue; thread locked!