I cam close to the boarder of the map (a giant wall of lapis) and my game suddenly crashed. I can not load it again. I tried 1.7.5 and 14w21b, and nothing worked. I had been playing the map for a while.

2nd Crash Report:
---- Minecraft Crash Report ----
// But it works on my machine.

Time: 6/14/14 4:23 PM
Description: Exception ticking world

java.lang.IllegalArgumentException: n must be positive
at java.util.Random.nextInt(Unknown Source)
at amy.a(SourceFile:72)
at azq.a(SourceFile:460)
at op.a(SourceFile:175)
at ayj.a(SourceFile:851)
at op.c(SourceFile:104)
at op.d(SourceFile:117)
at alk.b(SourceFile:290)
at oq.h(SourceFile:305)
at oq.c(SourceFile:196)
at net.minecraft.server.MinecraftServer.w(SourceFile:570)
at net.minecraft.server.MinecraftServer.v(SourceFile:506)
at cln.v(SourceFile:132)
at net.minecraft.server.MinecraftServer.run(SourceFile:422)
at java.lang.Thread.run(Unknown Source)

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

– Head –
Stacktrace:
at java.util.Random.nextInt(Unknown Source)
at amy.a(SourceFile:72)
at azq.a(SourceFile:460)
at op.a(SourceFile:175)
at ayj.a(SourceFile:851)
at op.c(SourceFile:104)
at op.d(SourceFile:117)
at alk.b(SourceFile:290)
at oq.h(SourceFile:305)
at oq.c(SourceFile:196)

– Affected level –
Details:
Level name: Super Hostile - Sunburn Islands
All players: 1 total; [ot['commandermatts'/456, l='Super Hostile - Sunburn Islands', x=-41.52, y=64.40, z=-512.20]]
Chunk stats: ServerChunkCache: 1269 Drop: 0
Level seed: 832172985
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options:
Level spawn location: 54.00,67.00,72.00 - World: (54,67,72), Chunk: (at 6,4,8 in 3,4; contains blocks 48,0,64 to 63,255,79), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 1290412 game time, 297562 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 124689 (now: false), thunder time: 139734 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.MinecraftServer.w(SourceFile:570)
at net.minecraft.server.MinecraftServer.v(SourceFile:506)
at cln.v(SourceFile:132)
at net.minecraft.server.MinecraftServer.run(SourceFile:422)
at java.lang.Thread.run(Unknown Source)

– System Details –
Details:
Minecraft Version: 14w21b
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.6.0_17, Sun Microsystems Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
Memory: 16197832 bytes (15 MB) / 201654272 bytes (192 MB) up to 954466304 bytes (910 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Profiler Position: N/A (disabled)
Player Count: 1 / 8; [ot['commandermatts'/456, l='Super Hostile - Sunburn Islands', x=-41.52, y=64.40, z=-512.20]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.