Friend on my server glitching/ clipping through the ground.

[OreoAftermath]

I have recently started a server and things have been going really well. The only issue I have had is my friend keeps glitching through the ground and he cant do anything about it. we've restarted everything, reinstalled everything. ive even teleported him into a different location but we are still having the same problem. Any advice or help? here is the log from the server... hope this helps.

2013-07-23 20:49:57 [iNFO] [Galacticraft] -28

2013-07-23 20:50:00 [iNFO] [ForgeModLoader] User grimmreaping connecting with mods [TradeBoothMod, OCS, DungeonPack, MineFactoryReloaded|CompatMystcraft, rftl, Magical-Crops, OmniTools, BuildCraft|Transport, MineFactoryReloaded|CompatBiomesOPlenty, MineFactoryReloaded|CompatRP2, ImmibisPeripherals, secretroomsmod, ICBM|Contraption, UsefulFood, MineFactoryReloaded|CompatMagicalCrops, ICBM|Sentry, ObsidiPlates, ArtificeCompat|EE3, MineFactoryReloaded|CompatSoulShards, MineFactoryReloaded|CompatNatura, CoFHWorld, TConstruct, Forestry, EnderStorage, BinnieCore, chococraft, MineFactoryReloaded|CompatAtum, BetterStorage, mmmPowersuits, GalacticraftCore, IronChest, MineFactoryReloaded|CompatThermalExpansion, BuildCraft|Energy, AtomicScience, EE3, ImmibisCore, GregsLighting, LogisticsPipes|Main, DimensionalDoors, MineFactoryReloaded|CompatAppliedEnergistics, MineFactoryReloaded|CompatXyCraft, AppliedEnergistics, mod_bspkrsCore, ArtificeCompat|MFR, MineFactoryReloaded, minechem, ThermalExpansion, PowersuitAddons, MineFactoryReloaded|CompatBackTools, MineFactoryReloaded|CompatForestryPre, inventorytweaks, BetterAnvil, NetherOres, BuildCraft|Silicon, APUnofficial, ArtificeCompat|Vanilla, MineFactoryReloaded|CompatIC2, MineFactoryReloaded|CompatVanilla, PamWeeeFlowers, Mekanism, BuildCraft|Core, DimensionalAnchors, MineFactoryReloaded|CompatPams, MekanismGenerators, MineFactoryReloaded|CompatExtraBiomes, ExtraBees, MekanismTools, Mystcraft, ComputerCraft, MineFactoryReloaded|CompatChococraft, TreeCapitator, MineFactoryReloaded|CompatTwilightForest, CoFHNetwork, BuildCraft|Factory, MFFS, Forge, bau5_ProjectBench, SoulShards, ICBM|Explosion, MFReloaded|CompatThaumcraft, MineFactoryReloaded|CompatForestry, CCTurtle, eplus, MineFactoryReloaded|CompatSufficientBiomes, BuildCraft|Builders, MineFactoryReloaded|CompatTConstruct]

2013-07-23 20:50:00 [iNFO] [Minecraft-Server] grimmreaping[/10.228.136.4:59763] logged in with entity id 113088 at (-970.0313195532925, 72.0099998950957, 160.5335610829487)

2013-07-23 20:50:00 [iNFO] [sTDOUT] Loading Player: grimmreaping

2013-07-23 20:50:00 [iNFO] [sTDOUT] Sending serverside check to: grimmreaping

2013-07-23 20:50:29 [iNFO] [sTDERR] java.net.SocketException: Socket closed

2013-07-23 20:50:29 [iNFO] [Minecraft-Server] grimmreaping lost connection: disconnect.quitting

2013-07-23 20:50:29 [iNFO] [sTDERR]at java.net.SocketOutputStream.socketWrite(Unknown Source)

2013-07-23 20:50:29 [iNFO] [sTDOUT] Unloading Player: grimmreaping

2013-07-23 20:50:29 [iNFO] [sTDERR]at java.net.SocketOutputStream.write(Unknown Source)

2013-07-23 20:50:29 [iNFO] [sTDERR]at org.bouncycastle.crypto.io.CipherOutputStream.write(Unknown Source)

2013-07-23 20:50:29 [iNFO] [sTDERR]at java.io.BufferedOutputStream.flushBuffer(Unknown Source)

2013-07-23 20:50:29 [iNFO] [sTDERR]at java.io.BufferedOutputStream.flush(Unknown Source)

2013-07-23 20:50:29 [iNFO] [sTDERR]at java.io.DataOutputStream.flush(Unknown Source)

2013-07-23 20:50:29 [iNFO] [sTDERR]at net.minecraft.network.TcpWriterThread.run(SourceFile:121)

2013-07-23 20:50:35 [FINEST] [ForgeModLoader] Received valid FML login packet from /10.228.136.4:59771

2013-07-23 20:50:35 [iNFO] [Galacticraft] -28

[Bothal]

I had this strange error - it occurred when a user built an Auto Farm and it went across a chunk border he was slipping between the chunks.

I actually had to restore the world directory to the previous back to fix it - I could never pinpoint what part/mod actually cause - sorry not much help but hopefully may give someone else an Idea.