Server problem

Suddenly a weird error came into my server :S dont know what cause it.

Code:

14:41:31 [INFO] Preparing level "Det lille samfund"
14:41:31 [SEVERE] java.io.IOException: Not in GZIP format
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.readHeader(Unknown Sour
ce)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at net.minecraft.server.NBTCompressedStreamTools.a(Sourc
eFile:9)
14:41:31 [SEVERE]       at net.minecraft.server.WorldLoader.b(SourceFile:52)
14:41:31 [SEVERE]       at net.minecraft.server.WorldLoaderServer.isConvertable(
SourceFile:94)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.a(MinecraftServe
r.java:199)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.init(MinecraftSe
rver.java:165)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:399)
14:41:31 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:457)
14:41:31 [SEVERE] java.io.IOException: Not in GZIP format
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.readHeader(Unknown Sour
ce)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at net.minecraft.server.NBTCompressedStreamTools.a(Sourc
eFile:9)
14:41:31 [SEVERE]       at net.minecraft.server.WorldLoader.b(SourceFile:63)
14:41:31 [SEVERE]       at net.minecraft.server.WorldLoaderServer.isConvertable(
SourceFile:94)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.a(MinecraftServe
r.java:199)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.init(MinecraftSe
rver.java:165)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:399)
14:41:31 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:457)
14:41:31 [INFO] Default game type: 0
14:41:31 [SEVERE] java.io.IOException: Not in GZIP format
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.readHeader(Unknown Sour
ce)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at net.minecraft.server.NBTCompressedStreamTools.a(Sourc
eFile:9)
14:41:31 [SEVERE]       at net.minecraft.server.WorldNBTStorage.getWorldData(Wor
ldNBTStorage.java:101)
14:41:31 [SEVERE]       at net.minecraft.server.World.<init>(World.java:157)
14:41:31 [SEVERE]       at net.minecraft.server.WorldServer.<init>(WorldServer.j
ava:27)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.a(MinecraftServe
r.java:242)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.init(MinecraftSe
rver.java:165)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:399)
14:41:31 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:457)
14:41:31 [SEVERE] java.io.IOException: Not in GZIP format
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.readHeader(Unknown Sour
ce)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at java.util.zip.GZIPInputStream.<init>(Unknown Source)
14:41:31 [SEVERE]       at net.minecraft.server.NBTCompressedStreamTools.a(Sourc
eFile:9)
14:41:31 [SEVERE]       at net.minecraft.server.WorldNBTStorage.getWorldData(Wor
ldNBTStorage.java:112)
14:41:31 [SEVERE]       at net.minecraft.server.World.<init>(World.java:157)
14:41:31 [SEVERE]       at net.minecraft.server.WorldServer.<init>(WorldServer.j
ava:27)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.a(MinecraftServe
r.java:242)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.init(MinecraftSe
rver.java:165)
14:41:31 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:399)
14:41:31 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:457)
14:41:31 [INFO] Unable to find spawn biome

 

Read this thread.

 

i dont think i understand MCEdit :S Can it fix my server?

 

No, but it might be able to fix your world, which is corrupt. You can also try using Chunkster, but MCEdit is your best bet.

If that fails, restore from backups. If you have no backups, start fresh.

 

How can i find the problem on my server, and how do i fix it by using MCEdit?

 

Just use chunkster