When I try to play on a server my game starts to load up the server but then it just crashes, and i don't know how to fix the problem.

What message ?

Incomplete without a crash report from ([minecraft/crash-reports/crash-<DATE>-client.txt|http://hopper.minecraft.net/help/finding-minecraft-data-folder]). Please attach it so that we can diagnose your issue.

Ohh ok ill attach the crash report

.....CRASH REPORT...

Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 7/31/14 7:11 PM
Description: Ticking screen

java.lang.IndexOutOfBoundsException
at java.nio.Buffer.checkIndex(Buffer.java:512)
at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:248)
at bma.a(SourceFile:271)
at bma.a(SourceFile:220)
at bao.a(SourceFile:1694)
at bao.a(SourceFile:1652)
at bjb.a(SourceFile:125)
at hd.a(SourceFile:70)
at hd.a(SourceFile:13)
at ej.a(SourceFile:174)
at bcx.e(SourceFile:78)
at bao.p(SourceFile:1343)
at bao.ak(SourceFile:774)
at bao.f(SourceFile:728)
at net.minecraft.client.main.Main.main(SourceFile:148)

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:512)
at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:248)
at bma.a(SourceFile:271)
at bma.a(SourceFile:220)
at bao.a(SourceFile:1694)
at bao.a(SourceFile:1652)
at bjb.a(SourceFile:125)
at hd.a(SourceFile:70)
at hd.a(SourceFile:13)
at ej.a(SourceFile:174)
at bcx.e(SourceFile:78)

– Affected screen –
Details:
Screen name: bcx

– 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: survival (ID 0). 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 bjf.a(SourceFile:289)
at bao.b(SourceFile:1972)
at bao.f(SourceFile:737)
at net.minecraft.client.main.Main.main(SourceFile:148)

– System Details –
Details:
Minecraft Version: 1.7.10
Operating System: Mac OS X (x86_64) version 10.9.4
Java Version: 1.6.0_65, Apple Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
Memory: 34377520 bytes (32 MB) / 85000192 bytes (81 MB) up to 1065025536 bytes (1015 MB)
JVM Flags: 1 total; -Xmx1G
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: 1.7.10
LWJGL: 2.9.1
OpenGL: Intel HD Graphics 3000 OpenGL Engine GL version 2.1 INTEL-8.24.15, Intel Inc.
GL Caps: Using GL 1.3 multitexturing.
Using framebuffer objects because ARB_framebuffer_object is supported and separate blending is supported.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: []
Current Language: English (UK)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Anisotropic Filtering: Off (1)

Can anyone help me please?

If you played in the snapshots, try reinstalling a fresh copy of Minecraft, that should fix the problem. Snapshots write newer versions of files than 1.7.10 can handle. Its advisable to have two separate folders for Minecraft, one for 1.7.10, and the other for 1.8 snapshots.

Im not sure what you want me to do?

Simply edit in .minecraft/options.txt the renderDistance: to anything below 16

Ok done thanks that fixed the problem thanks again.