singleplayer

In the singleplayer when I open or create any world tells me that the game has crashed

---- Minecraft Crash Report ----
// Quite honestly, I wouldn't worry myself about that.

Time: 24/08/14 10.20
Description: Starting integrated server

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1
	at com.google.gson.Gson.fromJson(Gson.java:815)
	at com.google.gson.Gson.fromJson(Gson.java:768)
	at ns.b(SourceFile:156)
	at ns.<init>(SourceFile:42)
	at net.minecraft.server.MinecraftServer.<init>(SourceFile:114)
	at bsx.<init>(SourceFile:38)
	at bao.a(SourceFile:1610)
	at bdb.a(SourceFile:202)
	at bdw.a(SourceFile:172)
	at bdb.a(SourceFile:301)
	at bdw.k(SourceFile:232)
	at bdw.p(SourceFile:211)
	at bao.p(SourceFile:1328)
	at bao.ak(SourceFile:774)
	at bao.f(SourceFile:728)
	at net.minecraft.client.main.Main.main(SourceFile:148)
Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1
	at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:338)
	at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:79)
	at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
	at com.google.gson.Gson.fromJson(Gson.java:803)
	... 15 more


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

-- Head --
Stacktrace:
	at com.google.gson.Gson.fromJson(Gson.java:815)
	at com.google.gson.Gson.fromJson(Gson.java:768)
	at ns.b(SourceFile:156)
	at ns.<init>(SourceFile:42)
	at net.minecraft.server.MinecraftServer.<init>(SourceFile:114)
	at bsx.<init>(SourceFile:38)

-- Starting integrated server --
Details:
	Level ID: Nuovo mondo----------
	Level Name: Nuovo mondo
Stacktrace:
	at bao.a(SourceFile:1610)
	at bdb.a(SourceFile:202)
	at bdw.a(SourceFile:172)
	at bdb.a(SourceFile:301)
	at bdw.k(SourceFile:232)
	at bdw.p(SourceFile:211)

-- Affected screen --
Details:
	Screen name: bee
Stacktrace:
	at bao.p(SourceFile:1328)
	at bao.ak(SourceFile:774)
	at bao.f(SourceFile:728)
	at net.minecraft.client.main.Main.main(SourceFile:148)

-- System Details --
Details:
	Minecraft Version: 1.7.10
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_67, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 44159440 bytes (42 MB) / 76087296 bytes (72 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: 0, tallocated: 0
	Launched Version: 1.7.10
	LWJGL: 2.9.1
	OpenGL: GeForce GT 520M/PCI/SSE2 GL version 4.1.0, NVIDIA Corporation
	GL Caps: Using GL 1.3 multitexturing.
Using framebuffer objects because OpenGL 3.0 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: Italiano (Italia)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Anisotropic Filtering: Off (1)