Probleme multijoueur

Bonjour a tous
jai un probleme sur minecraft quand je vais dans multijoueur et que j entre une adresse ip (funcraft.fr ou autre)
sa recherche et ma page minecraft se ferme sa fait eussi la meme chose avec le launcher asenctia je clique sur funcraft .fr sa recherche et se ferme le crash :


---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 04/05/14 11:15
Description: Unexpected error

java.lang.NullPointerException: Unexpected error
at Ay.a(Unknown Source)
at mk.f(Unknown Source)
at mk.aB(Unknown Source)
at lO.by(Unknown Source)
at lO.gZ(Unknown Source)
at lO.bv(Unknown Source)
at net.minecraft.client.main.Main.main(Unknown Source)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- System Details --
Details:
Minecraft Version: 1.7.2
Operating System: Windows Vista (x86) version 6.0
Java Version: 1.7.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
Memory: 33575248 bytes (32 MB) / 67952640 bytes (64 MB) up to 518979584 bytes (494 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.7.2
LWJGL: 2.9.0
OpenGL: GeForce 8400 GS/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
Is Modded: Very likely; Jar signature invalidated
Type: Client (map_client.txt)
Resource Packs: []
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
Anisotropic Filtering: Off (1)

j'espere que j aurai une reponnse au plus vite merci .