Explain this error?

I'm running bukkit 1.7.5 and this error is popping up in my server log, i want to get rid of this because I'm having random lag spikes and i think this is whats causing it.

Code:

3.04 07:25:17 [Server] INFO [03:25:17 WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 3167ms behind, skipping 63 tick(s)
13.04 07:25:15 [03:25:14 INFO]: Monk3y4 ran command Message of the Day
13.04 07:25:14 [03:25:14 INFO]: akiracheese ran command Message of the Day
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.ThreadServerApplication.run(SourceFile:618)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.MinecraftServer.run(MinecraftServer.java:459)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.MinecraftServer.u(MinecraftServer.java:548)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.DedicatedServer.v(DedicatedServer.java:250)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.MinecraftServer.v(MinecraftServer.java:597)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at org.bukkit.craftbukkit.v1_7_R2.chunkio.ChunkIOExecutor.tick(ChunkIOExecutor.java:34)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at org.bukkit.craftbukkit.v1_7_R2.util.AsynchronousExecutor.finishActive(AsynchronousExecutor.java:347)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at org.bukkit.craftbukkit.v1_7_R2.util.AsynchronousExecutor$Task.finish(AsynchronousExecutor.java:188)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at org.bukkit.craftbukkit.v1_7_R2.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:13)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at org.bukkit.craftbukkit.v1_7_R2.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:37)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.ChunkRegionLoader.loadEntities(ChunkRegionLoader.java:388)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.Chunk.a(Chunk.java:665)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]:    at net.minecraft.server.v1_7_R2.Chunk.a(Chunk.java:690)
13.04 07:25:14 [Server] INFO [03:25:14 WARN]: java.lang.Exception
13.04 07:25:14 [Server] INFO [03:25:14 INFO]: Chunk coordinates: -20112,-20032
13.04 07:25:14 [Server] INFO [03:25:14 INFO]: Attempted to place a tile entity (net.minecraft.server.v1_7_R2.TileEntityComparator@26d01270) at -20105,74,-20025 (AIR) where there was no entity tile!
13.04 07:25:14 [03:25:14 INFO]: Derpy_Waffle ran command Message of the Day
13.04 07:25:14 [Connect] User [03:25:14 INFO]: Monk3y4, IP 99.46.176.223
13.04 07:25:14 [Server] INFO [03:25:14 INFO]: Loaded player file for Monk3y4
13.04 07:25:14 [Connect] User [03:25:14 INFO]: akiracheese, IP 98.207.61.231
13.04 07:25:14 [Server] INFO [03:25:14 INFO]: Loaded player file for akiracheese
13.04 07:25:14 [03:25:13 INFO]: killerbry7 ran command Message of the Day
13.04 07:25:14 [Connect] User [03:25:14 INFO]: Derpy_Waffle, IP 64.231.18.15
13.04 07:25:14 [Server] INFO [03:25:14 INFO]: [MythicMobs] A new version of MythicMobs is available: MythicMobs: Quests v0.3
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: Loaded player file for Derpy_Waffle
13.04 07:25:13 [Connect] User [03:25:13 INFO]: killerbry7, IP 71.198.98.91
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: [MythicMobs] A new version of MythicMobs is available: MythicMobs: Quests v0.3
13.04 07:25:13 [03:25:13 INFO]: NoFatAsiansPlz ran command Message of the Day
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: Loaded player file for killerbry7
13.04 07:25:13 [Connect] User [03:25:13 INFO]: NoFatAsiansPlz, IP 99.8.158.111
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: [WorldGuard] 1 regions loaded for 'skyworld'
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: [MythicMobs] A new version of MythicMobs is available: MythicMobs: Quests v0.3
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: Loaded player file for NoFatAsiansPlz
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: UUID of player Monk3y4 is ab052e60383d43e0a331880d5702d378
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: UUID of player killerbry7 is 867c3e71f61d4d7e8c82bf39afc1916d
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: UUID of player Derpy_Waffle is 2a9ce4836c924f70b923eff0f9e03ebf
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: UUID of player akiracheese is 40125366954a4047b70c7ac9c8fd8bc7
13.04 07:25:13 [Server] INFO [03:25:13 INFO]: UUID of player NoFatAsiansPlz is 384e3f375c3f468bb6164dbe8bc7fd18
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [WorldGuard] 2 regions loaded for 'Hub'
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: ----------------------------------------------------------
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [ChestCommands] Invalid item-id "" in the file "Skyblock.yml".
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [ChestCommands] Invalid item-id "" in the file "KitPvP.yml".
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: ----------------------------------------------------------
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: GroupManager - INFO - Bukkit Permissions Updated!
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [Multiverse-Inventories] Conflicts have been found... If these are not resolved, you may experience problems with your data.
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [Multiverse-Inventories] Conflict found for groups: 'default' and 'Skyblock' because they both share: 'hit_points, economy, food_level, saturation, exhaustion, xp, total_xp, lvl, inventory_contents, armor_contents, bed_spawn, maximum_air, remaining_air, fall_distance, fire_ticks, potion_effects, last_location, ender_chest' for the world(s): 'vip, skyarena'
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [PlugMan] No update was found.
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [LWC] [LWC] This can probably be ignored.
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [LWC] [LWC] The updater ran into a minor issue: http://update.griefcraft.com/lwc/branch/stable/LATEST
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [PlugMan] Metrics started: http://mcstats.org/plugin/PlugMan
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [NoCheatPlus] Post-enable finished.
13.04 07:25:11 [Server] INFO [03:25:11 INFO]: [NoCheatPlus] Post-enable running...
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [Jobs] [Jobs] Successfully linked with Vault.
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: Accepted EditSessionFactory of type net.coreprotect.worldedit.CoreProtectEditSessionFactory from net.coreprotect.worldedit
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: Multiverse already knows about 'skyworld'!
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [uSkyBlock] Using vault for permissions
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: Query running on 76.164.198.235:25565
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: Starting GS4 status listener
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: Done (28.785s)! For help, type "help" or "?"
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: Server permissions file permissions.yml is empty, ignoring it
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [Multiverse-NetherPortals] - Version 2.5-b668 Enabled - By Rigby and fernferret
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [Multiverse-NetherPortals] Enabling Multiverse-NetherPortals v2.5-b668
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [MythicMobs] A new version of MythicMobs is available: MythicMobs: Quests v0.3
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [MythicMobs] v0.10.5 has been successfully loaded!
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [MythicMobs] MythicMobs WorldGuard Support has been enabled!
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [MythicMobs] MythicMobs Vault Support has been enabled!
13.04 07:25:10 [Server] INFO [03:25:10 INFO]: [MythicMobs] MythicMobs MobArena Support has been enabled!
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loaded 3 mob spawners.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loaded 4 drop tables.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loaded 8 mythic items.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loaded 1 random spawns.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loaded 7 skills.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loaded 0 mob stacks.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loaded 8 mobs.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Loading MythicMobs...
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MythicMobs] Enabling MythicMobs v0.10.5
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [HolographicDisplays] Enabling HolographicDisplays v1.4.3
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MobArena] v0.96.3 enabled.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MobArena] Loaded arena 'default'
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MobArena] Loaded arena 'traitonarena'
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MobArena] Loaded arena 'slumarena'
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MobArena] Vault found; economy rewards enabled.
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MobArena] Enabling MobArena v0.96.3
13.04 07:25:08 [Server] INFO [03:25:08 WARN]: [Multiverse-Core] Portal Parkour has an invalid DESTINATION!
13.04 07:25:08 [Server] INFO [03:25:08 INFO]: [MVPLogging] 8 - Portals(s) loaded
13.04 07:25:08 [Server] INFO [03:25:08 WARN]: [MVPLogging] Portal 'Parkour1' not loaded due to invalid location!
13.04 07:25:08 [Server] INFO [03:25:08 WARN]: [MVPLogging] Portal Parkour1 has an invalid LOCATION!
13.04 07:25:08 [Server] INFO [03:25:08 WARN]: [MVPLogging] Failed Parsing World for: Parkour1 (World Error, World did not exist or was not imported into Multiverse-Core!)
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-Portals] - Version 2.5-b697 Enabled - By Rigby and fernferret
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-Portals] Enabling Multiverse-Portals v2.5-b697
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-SignPortals 2.5-b656]  Enabled - By Rigby and fernferret
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-SignPortals] Enabling Multiverse-SignPortals v2.5-b656
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-Inventories 2.5-b357] enabled.
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-Inventories] The following worlds for group 'Skyblock' are not loaded: VIP, SkyArena
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-Inventories] The following worlds for group 'default' are not loaded: VIP, SkyArena
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Multiverse-Inventories] Enabling Multiverse-Inventories v2.5-b357
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [PlayerHeads] Enabling PlayerHeads v3.8-jenkins-PlayerHeads-1-48-ged24b6b
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Fly_Payment] Made By AhellHound
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Fly_Payment] Fly_Payment version 3.2 is now enabled.
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Fly_Payment] Enabling Fly_Payment v3.2
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Parkour] Linked with Economy v1.2.27-b349
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Parkour] 3.0 Enabled!
13.04 07:25:07 [Server] INFO [03:25:07 INFO]: [Parkour] Enabling Parkour v3.0
13.04 07:25:06 [Server] INFO [03:25:06 INFO]: [Residence] Enabled! Version 2.6.6.6 by bekvon
13.04 07:25:06 [Server] INFO [03:25:06 INFO]: [Residence] Found WorldEdit
13.04 07:25:05 [Server] INFO [03:25:05 INFO]: [Residence] Found Vault using economy system: Essentials Economy
13.04 07:25:05 [Server] INFO [03:25:05 INFO]: [Residence] Scanning for economy systems...

 

Looks like a bad chunk to me.
I recommend getting NoLagg.

 

Thats really all it is, just a chunk that isn't loading properly.

 

Ahhhh! alright thanks