It is unknown what caused these crashes but this is the report that I got:

---- Minecraft Crash Report ----
// Surprise! Haha. Well, this is awkward.

Time: 7/2/14 12:30 PM
Description: Unexpected error

java.lang.NullPointerException: Unexpected error
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:192)
at com.google.common.collect.Lists.newArrayList(Lists.java:126)
at bcc.a(SourceFile:144)
at bcc.a(SourceFile:123)
at bcc.a(SourceFile:119)
at bjb.a(SourceFile:474)
at gj.a(SourceFile:38)
at gj.a(SourceFile:9)
at ej.a(SourceFile:174)
at bje.e(SourceFile:212)
at bao.p(SourceFile:1306)
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 com.google.common.base.Preconditions.checkNotNull(Preconditions.java:192)
at com.google.common.collect.Lists.newArrayList(Lists.java:126)
at bcc.a(SourceFile:144)
at bcc.a(SourceFile:123)
at bcc.a(SourceFile:119)
at bjb.a(SourceFile:474)
at gj.a(SourceFile:38)
at gj.a(SourceFile:9)
at ej.a(SourceFile:174)
at bje.e(SourceFile:212)

– Affected level –
Details:
Level name: MpServer
All players: 3 total; [bjk['CommanderOx'/690, l='MpServer', x=-74.45, y=70.62, z=2948.39], bll['GingyGirl'/39485, l='MpServer', x=-72.69, y=64.03, z=2951.50], bll['nickisgunpowder'/46225, l='MpServer', x=-75.22, y=64.36, z=2933.69]]
Chunk stats: MultiplayerChunkCache: 121, 121
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (1228,86,260), Chunk: (at 12,5,4 in 76,16; contains blocks 1216,0,256 to 1231,255,271), Region: (2,0; contains chunks 64,0 to 95,31, blocks 1024,0,0 to 1535,255,511)
Level time: 361857894 game time, 457083560 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: 31 total; [wh['Cow'/39512, l='MpServer', x=-108.22, y=72.00, z=2918.11], yq['Zombie'/46588, l='MpServer', x=-115.88, y=53.00, z=2988.25], yq['Zombie'/46876, l='MpServer', x=-99.50, y=30.00, z=2904.50], bjk['CommanderOx'/690, l='MpServer', x=-74.45, y=70.62, z=2948.39], wh['Cow'/39505, l='MpServer', x=-113.75, y=63.00, z=2964.78], yl['Skeleton'/46878, l='MpServer', x=-84.50, y=29.00, z=2926.50], xz['Creeper'/46790, l='MpServer', x=-44.50, y=40.00, z=2958.50], wo['Pig'/39508, l='MpServer', x=-82.91, y=65.00, z=2938.85], bll['GingyGirl'/39485, l='MpServer', x=-72.69, y=64.03, z=2951.50], wh['Cow'/39497, l='MpServer', x=-104.31, y=60.00, z=2987.47], xz['Creeper'/46019, l='MpServer', x=-118.31, y=53.00, z=2985.91], wg['Chicken'/39501, l='MpServer', x=-65.44, y=29.00, z=2904.43], xk['item.item.rottenFlesh'/45477, l='MpServer', x=-78.03, y=66.13, z=2967.00], wh['Cow'/39502, l='MpServer', x=-47.29, y=69.47, z=2955.51], bll['nickisgunpowder'/46225, l='MpServer', x=-75.22, y=64.36, z=2933.69], xz['Creeper'/45965, l='MpServer', x=-63.50, y=25.00, z=2922.50], xz['Creeper'/39488, l='MpServer', x=-95.47, y=62.08, z=2970.91], wh['Cow'/39490, l='MpServer', x=-63.25, y=68.00, z=2969.47], bll['johnnymeboy'/39552, l='MpServer', x=-68.94, y=66.00, z=2933.66], yp['Witch'/39492, l='MpServer', x=-59.22, y=67.00, z=2979.25], xz['Creeper'/46805, l='MpServer', x=-58.50, y=19.00, z=2940.50], yn['Spider'/45962, l='MpServer', x=-87.50, y=29.00, z=2925.50], wo['Pig'/39494, l='MpServer', x=-98.06, y=63.00, z=2964.38], wh['Cow'/39487, l='MpServer', x=-76.42, y=67.00, z=2972.42], bll['GingyGirl'/39485, l='MpServer', x=-72.69, y=64.03, z=2951.50], wh['Cow'/39551, l='MpServer', x=-116.03, y=71.00, z=2916.94], wo['Pig Pet'/40700, l='MpServer', x=-76.50, y=69.00, z=2944.63], xz['Creeper'/46697, l='MpServer', x=-85.00, y=17.00, z=2987.41], yq['Zombie'/45810, l='MpServer', x=-108.69, y=59.00, z=2938.97], bll['nickisgunpowder'/46225, l='MpServer', x=-75.22, y=64.36, z=2933.69], wo['Pig Pet'/46231, l='MpServer', x=-75.25, y=65.00, z=2942.47]]
Retry entities: 0 total; []
Server brand: Spigot
Server type: Non-integrated multiplayer server
Stacktrace:
at bjf.a(SourceFile:289)
at bao.b(SourceFile:1972)
at bao.f(SourceFile:742)
at net.minecraft.client.main.Main.main(SourceFile:148)

– System Details –
Details:
Minecraft Version: 1.7.10
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: 29770536 bytes (28 MB) / 125595648 bytes (119 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: 13, tallocated: 95
Launched Version: 1.7.10
LWJGL: 2.9.1
OpenGL: Intel Bear Lake B GL version 1.4.0 - Build 7.14.10.1437, Intel
GL Caps: Using GL 1.3 multitexturing.
Not using framebuffer objects because OpenGL 1.4 is not supported, EXT_blend_func_separate is supported, OpenGL 3.0 is not supported, ARB_framebuffer_object is not supported, and EXT_framebuffer_object is not supported.
Anisotropic filtering is supported and maximum anisotropy is 4.
Shaders are not available because OpenGL 2.1 is not supported, ARB_shader_objects is not supported, ARB_vertex_shader is not supported, and ARB_fragment_shader is not supported.

Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: [OxCorp Essentials Pack]
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)