Problem Help... Internal server error fix needed!!!

[Rozz]

Im running my FTB ultimate server on windows 7 64 bit java, and every time i connect to my server i get internal server error some times its as soon as i sign in and other times i can play for a bit then it comes up with the error, anyone no what this is?
Also not sure if this is 100% the case but it happens when i open up my inventory buy pressing 'E'.

this comes up in the java log and chat:

java.lang.NullPointerException
at codechicken.enderstorage.api.EnderStorageManager.getStorage(EnderStorageManager.java:237)
at codechicken.enderstorage.storage.liquid.TankSynchroniser$PlayerItemTankCache.track(TankSynchroniser.java:170)
at codechicken.enderstorage.storage.liquid.TankSynchroniser$PlayerItemTankCache.handleVisiblityPacket(TankSynchroniser.java:230)
at codechicken.enderstorage.storage.liquid.TankSynchroniser.handleVisiblityPacket(TankSynchroniser.java:267)
at codechicken.enderstorage.internal.EnderStorageSPH.handlePacket(EnderStorageSPH.java:21)
at codechicken.core.packet.PacketCustom$ServerPacketHandler.handle(PacketCustom.java:124)
at codechicken.core.packet.PacketCustom$CustomPacketHandler.onPacketData(PacketCustom.java:73)
at cpw.mods.fml.common.network.NetworkRegistry.handlePacket(NetworkRegistry.java:243)
at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:233)
at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHand
[14:10:52] >>ler.java:71)
at iv.a(NetServerHandler.java:1110)
at di.a(SourceFile:59)
at cg.b(TcpConnection.java:458)
at iv.d(NetServerHandler.java:136)
at iw.b(NetworkListenThread.java:57)
at ht.b(SourceFile:30)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:703)
at ho.r(DedicatedServer.java:269)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:599)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)
at fy.run(SourceFile:849)