Signs get " and \" every Worldload

Minecraft Crash Report ----
// Ooh. Shiny.

Time: 29.07.15 18:52
Description: Rendering Block Entity

java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOfRange(Arrays.java:3664)
at java.lang.String.<init>(String.java:201)
at java.lang.StringBuilder.toString(StringBuilder.java:407)
at axt.a(SourceFile:40)
at bjx.a(SourceFile:88)
at bjx.a(SourceFile:18)
at bjq.a(SourceFile:116)
at bjq.a(SourceFile:104)
at bht.a(SourceFile:627)
at bhm.a(SourceFile:1214)
at bhm.b(SourceFile:1119)
at bhm.a(SourceFile:1000)
at axc.at(SourceFile:900)
at axc.a(SourceFile:323)
at net.minecraft.client.main.Main.main(SourceFile:125)

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

– Head –
Stacktrace:
at java.util.Arrays.copyOfRange(Arrays.java:3664)
at java.lang.String.<init>(String.java:201)
at java.lang.StringBuilder.toString(StringBuilder.java:407)
at axt.a(SourceFile:40)
at bjx.a(SourceFile:88)
at bjx.a(SourceFile:18)

– Block Entity Details –
Details:
Name: Sign // amx
Block type: ID #68 (tile.sign // alw)
Block data value: 4 / 0x4 / 0b0100
Block location: World: (-8,65,-218), Chunk: (at 8,4,6 in -1,-14; contains blocks -16,0,-224 to -1,255,-209), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Actual block type: ID #68 (tile.sign // alw)
Actual block data value: 4 / 0x4 / 0b0100
Stacktrace:
at bjq.a(SourceFile:116)
at bjq.a(SourceFile:104)
at bht.a(SourceFile:627)
at bhm.a(SourceFile:1214)
at bhm.b(SourceFile:1119)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bgz['Iruini'/183, l='MpServer', x=-35,97, y=83,85, z=-251,23]]
Chunk stats: MultiplayerChunkCache: 30, 30
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: 0,00,64,00,0,00 - World: (0,64,0), Chunk: (at 0,4,0 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: 43300562 game time, 1732414 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: 11 total; [vk['Boot'/20016, l='MpServer', x=-0,84, y=64,50, z=-209,53], bgz['Iruini'/183, l='MpServer', x=-35,97, y=83,85, z=-251,23], vb['entity.LeashKnot.name'/178, l='MpServer', x=56,50, y=86,50, z=-119,50], vb['entity.LeashKnot.name'/179, l='MpServer', x=56,50, y=86,50, z=-123,50], uc['Ozelot'/185, l='MpServer', x=-74,16, y=68,00, z=-274,59], uc['Ozelot'/186, l='MpServer', x=-73,50, y=69,00, z=-270,50], tu['Fledermaus'/20010, l='MpServer', x=-34,10, y=42,14, z=-212,75], uc['Ozelot'/188, l='MpServer', x=-59,56, y=67,00, z=-286,16], uc['Ozelot'/189, l='MpServer', x=-62,50, y=67,00, z=-284,50], uc['Ozelot'/190, l='MpServer', x=-57,59, y=68,16, z=-285,31], uc['Ozelot'/191, l='MpServer', x=-54,19, y=75,00, z=-275,59]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bfb.a(SourceFile:309)
at axc.b(SourceFile:2293)
at axc.a(SourceFile:332)
at net.minecraft.client.main.Main.main(SourceFile:125)

– System Details –
Details:
Minecraft Version: 15w31a
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: 849568816 bytes (810 MB) / 1060372480 bytes (1011 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
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 15w31a
LWJGL: 2.9.4
OpenGL: GeForce GTX 660/PCIe/SSE2 GL version 4.4.0, NVIDIA Corporation
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: Deutsch (Deutschland)
Profiler Position: N/A (disabled)
CPU: 8x Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz