Bukkit repeats a script then kicks everyone

sometimes it doesn't repeat the script, but after 3 minutes of playing, everyone gets kicked from the server. the script is

2012-07-18 21:11:35 [INFO] Attempted to place a tile entity (net.minecraft.server.TileEntitySign@1f5e4b6) at 557,21,601 (AIR) where there was no entity tile!
2012-07-18 21:11:35 [INFO] Chunk coordinates: 544,592
2012-07-18 21:11:35 [SEVERE] java.lang.Exception
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.Chunk.a(Chunk.java:627)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.Chunk.a(Chunk.java:606)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.ChunkRegionLoader.a(ChunkRegionLoader.java:293)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.ChunkRegionLoader.a(ChunkRegionLoader.java:63)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.ChunkRegionLoader.a(ChunkRegionLoader.java:52)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.ChunkProviderServer.loadChunk(ChunkProviderServer.java:135)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:78)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.PlayerInstance.<init>(PlayerInstance.java:26)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.PlayerManager.a(PlayerManager.java:60)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.PlayerManager.movePlayer(PlayerManager.java:156)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.ServerConfigurationManager.d(ServerConfigurationManager.java:169)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:412)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.Packet10Flying.handle(SourceFile:126)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.NetworkManager.b(NetworkManager.java:229)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:113)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:567)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:459)
2012-07-18 21:11:35 [SEVERE] at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)

and it repeats it about 50 times then kicks everyone and no one can get back in. i deleted our player.dats, added more RAM to the .bat, set priority to high on the server and above normal on my minecraft, and still nothing. so im asking for help.