You need to give a lot more than that...like can you print the error screen, or give the server properties, or the message you get when you crash?
The more info the better.
The meesage after crashing:
---- Minecraft Crash Report ----
// Ooh. Shiny.
Time: 8/03/15 01:50 PM
Description: Ticking screen
java.lang.IndexOutOfBoundsException
at java.nio.Buffer.checkIndex(Buffer.java:540)
at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:253)
at bls.a(SourceFile:270)
at bls.a(SourceFile:220)
at azd.a(SourceFile:1675)
at azd.a(SourceFile:1633)
at biv.a(SourceFile:113)
at gu.a(SourceFile:70)
at gu.a(SourceFile:13)
at ef.a(SourceFile:164)
at bbe.c(SourceFile:76)
at azd.o(SourceFile:1318)
at azd.ad(SourceFile:753)
at azd.e(SourceFile:704)
at net.minecraft.client.main.Main.main(SourceFile:103)
A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------
-- Head --
Stacktrace:
at java.nio.Buffer.checkIndex(Buffer.java:540)
at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:253)
at bls.a(SourceFile:270)
at bls.a(SourceFile:220)
at azd.a(SourceFile:1675)
at azd.a(SourceFile:1633)
at biv.a(SourceFile:113)
at gu.a(SourceFile:70)
at gu.a(SourceFile:13)
at ef.a(SourceFile:164)
at bbe.c(SourceFile:76)
-- Affected screen --
Details:
Screen name: bbe
-- Affected level --
Details:
Level name: MpServer
All players: 0 total; []
Chunk stats: MultiplayerChunkCache: 0, 0
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (8,64,8), Chunk: (at 8,4,8 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 0 game time, 0 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Forced entities: 0 total; []
Retry entities: 0 total; []
Server brand: ~~ERROR~~ NullPointerException: null
Server type: Non-integrated multiplayer server
Stacktrace:
at biz.a(SourceFile:284)
at azd.b(SourceFile:1951)
at azd.e(SourceFile:713)
at net.minecraft.client.main.Main.main(SourceFile:103)
-- System Details --
Details:
Minecraft Version: 1.7.2
Operating System: Windows 8.1 (amd64) version 6.3
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 66331384 bytes (63 MB) / 186605568 bytes (177 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
AABB Pool Size: 18497 (1035832 bytes; 0 MB) allocated, 18497 (1035832 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.7.2
LWJGL: 2.9.0
OpenGL: Intel(R) HD Graphics 4400 GL version 4.2.0 - Build 10.18.10.3496, Intel
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: []
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Anisotropic Filtering: Off (1)