Linked Nether Portals

I'm not sure if the pertains to Bukkit or if it's something else but for some reason our server is having some trouble with nether portals being linked, regardless of distance between them. An example would be a portal at my home (Coords: x=19 z=-4) taking me into the nether correctly, but when i re-enter the portal to go back to the main world, I end up at my friends house which is at x=839 z=-375. Any ideas what this could be? Maybe a plugin that is known for causing this issue or a bukkit config node? I'll post any information you guys require.

Thanks in advanced!

~Alex

My plugins are as followed:

AntiAdvertiser
BarAPI
BattleArena
BattleTracker
BetterLeads
Bloodshed
ChestShop
ChopTree2
CoreProtect
dynmap
EnchantMore
Essentials
Factions
HeavySpleef
iConomy
Lockette
mcMMO
mcore
OPLock
PermissionsEx
PersonalHorses
pvparena
ShowCaseStandalone
ServerSigns
Shopkeepers
SignCodePad
SilkSpawners
SimpleRestart
TrailofBlood
TreeAssist
Vault
VillagerNames
WorldEdit
WorldGuard

Hope this helps!​