Minecraft crash en version 1.8.8

Bonjour, Mon minecraft crash depuis 2 jours mais en jeu : au bout de 2 minutes de jeu ,minecraft crash .... Voici le crash report :

[10:50:35] [Client thread/INFO]: Setting user: iTweester
[10:50:35] [Client thread/INFO]: (Session ID is token:a197ce2f42bf4493a02fc6d776eca322:5dd07f537b094ec9a1345867796fb7dd)
[10:50:37] [Client thread/INFO]: LWJGL Version: 2.9.4
[10:50:38] [Client thread/INFO]: Reloading ResourceManager: Default
[10:50:39] [Sound Library Loader/INFO]: Starting up SoundSystem...
[10:50:40] [Thread-6/INFO]: Initializing LWJGL OpenAL
[10:50:40] [Thread-6/INFO]: (The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
[10:50:40] [Thread-6/INFO]: OpenAL initialized.
[10:50:40] [Sound Library Loader/INFO]: Sound engine started
[10:50:49] [Client thread/INFO]: Created: 512x512 textures-atlas
[10:50:51] [Client thread/ERROR]: Exception reading C:\Users\michel\AppData\Roaming\.minecraft\saves\World in a Jar\level.dat
java.util.zip.ZipException: Not in GZIP format
at java.util.zip.GZIPInputStream.readHeader(Unknown Source) ~[?:1.8.0_60]
at java.util.zip.GZIPInputStream.<init>(Unknown Source) ~[?:1.8.0_60]
at java.util.zip.GZIPInputStream.<init>(Unknown Source) ~[?:1.8.0_60]
at dx.a(SourceFile:13) ~[1.8.8.jar:?]
at atn.c(SourceFile:62) [1.8.8.jar:?]
at atk.b(SourceFile:52) [1.8.8.jar:?]
at axv.f(SourceFile:87) [1.8.8.jar:?]
at axv.b(SourceFile:59) [1.8.8.jar:?]
at axu.a(SourceFile:376) [1.8.8.jar:?]
at ave.a(SourceFile:819) [1.8.8.jar:?]
at aya.a(SourceFile:215) [1.8.8.jar:?]
at axu.a(SourceFile:350) [1.8.8.jar:?]
at aya.a(SourceFile:468) [1.8.8.jar:?]
at axu.k(SourceFile:413) [1.8.8.jar:?]
at axu.p(SourceFile:390) [1.8.8.jar:?]
at ave.s(SourceFile:1498) [1.8.8.jar:?]
at ave.av(SourceFile:889) [1.8.8.jar:?]
at ave.a(SourceFile:325) [1.8.8.jar:?]
at net.minecraft.client.main.Main.main(SourceFile:124) [1.8.8.jar:?]
[10:50:51] [Client thread/ERROR]: Exception reading C:\Users\michel\AppData\Roaming\.minecraft\saves\World in a Jar\level.dat_old
java.util.zip.ZipException: Not in GZIP format
at java.util.zip.GZIPInputStream.readHeader(Unknown Source) ~[?:1.8.0_60]
at java.util.zip.GZIPInputStream.<init>(Unknown Source) ~[?:1.8.0_60]
at java.util.zip.GZIPInputStream.<init>(Unknown Source) ~[?:1.8.0_60]
at dx.a(SourceFile:13) ~[1.8.8.jar:?]
at atn.c(SourceFile:73) [1.8.8.jar:?]
at atk.b(SourceFile:52) [1.8.8.jar:?]
at axv.f(SourceFile:87) [1.8.8.jar:?]
at axv.b(SourceFile:59) [1.8.8.jar:?]
at axu.a(SourceFile:376) [1.8.8.jar:?]
at ave.a(SourceFile:819) [1.8.8.jar:?]
at aya.a(SourceFile:215) [1.8.8.jar:?]
at axu.a(SourceFile:350) [1.8.8.jar:?]
at aya.a(SourceFile:468) [1.8.8.jar:?]
at axu.k(SourceFile:413) [1.8.8.jar:?]
at axu.p(SourceFile:390) [1.8.8.jar:?]
at ave.s(SourceFile:1498) [1.8.8.jar:?]
at ave.av(SourceFile:889) [1.8.8.jar:?]
at ave.a(SourceFile:325) [1.8.8.jar:?]
at net.minecraft.client.main.Main.main(SourceFile:124) [1.8.8.jar:?]
[10:50:54] [Server thread/INFO]: Starting integrated minecraft server version 1.8.8
[10:50:54] [Server thread/INFO]: Generating keypair
[10:50:54] [Server thread/INFO]: Preparing start region for level 0
[10:50:55] [Server thread/INFO]: Changing view distance to 16, from 10
[10:50:55] [Server thread/INFO]: iTweester[local:E:cf8cc602] logged in with entity id 45 at (96.79331044100009, 50.0, 0.3000000119209295)
[10:50:55] [Server thread/INFO]: iTweester joined the game
[10:51:01] [Client thread/INFO]: [CHAT] You do not have permission to use this command
[10:51:02] [Server thread/INFO]: Saving and pausing game...
[10:51:02] [Server thread/INFO]: Saving chunks for level 'Stratosphere Survival'/Overworld
[10:51:02] [Server thread/INFO]: Saving chunks for level 'Stratosphere Survival'/Nether
[10:51:02] [Server thread/INFO]: Saving chunks for level 'Stratosphere Survival'/The End
[10:51:04] [Client thread/INFO]: Using default channel type
[10:51:04] [Client thread/INFO]: Started on 50757
[10:51:04] [Client thread/INFO]: [CHAT] Local game hosted on port 50757
[10:51:06] [Server thread/INFO]: iTweester fell out of the world
[10:51:06] [Server thread/INFO]: [iTweester: Killed iTweester]
[10:51:06] [Client thread/INFO]: [CHAT] iTweester fell out of the world
[10:51:06] [Client thread/INFO]: [CHAT] Killed iTweester
[10:51:07] [pool-2-thread-1/ERROR]: Signature is missing from textures payload
[10:51:14] [Chunk Batcher 1/WARN]: Needed to grow BufferBuilder buffer: Old size 524288 bytes, new size 2621440 bytes.
[10:51:42] [Chunk Batcher 0/WARN]: Needed to grow BufferBuilder buffer: Old size 524288 bytes, new size 2621440 bytes.
[10:51:46] [Chunk Batcher 0/WARN]: Needed to grow BufferBuilder buffer: Old size 524288 bytes, new size 2621440 bytes.

Merci d'avance svp aidez moi je suis youtuber minecraft et la, c'est problématique