Not able to create new worlds, or load old worlds.

I have the exact same issue, I deleted my entire .minecraft and it still wouldn't work, I don't know if this will help but heres a crash report

---- Minecraft Crash Report ----
// I feel sad now :(

Time: 10/26/13 1:21 PM
Description: Starting integrated server

java.lang.ExceptionInInitializerError
	at net.minecraft.server.MinecraftServer.<init>(SourceFile:114)
	at bsk.<init>(SourceFile:38)
	at azd.a(SourceFile:1591)
	at bbi.a(SourceFile:202)
	at bcd.a(SourceFile:172)
	at bbi.a(SourceFile:301)
	at bcd.d(SourceFile:236)
	at bcd.k(SourceFile:211)
	at azd.o(SourceFile:1303)
	at azd.ad(SourceFile:753)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)
Caused by: java.lang.IllegalStateException: failed to create a child event loop
	at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:61)
	at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:49)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:61)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:52)
	at ms.<clinit>(SourceFile:31)
	... 12 more
Caused by: io.netty.channel.ChannelException: failed to open a new selector
	at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:128)
	at io.netty.channel.nio.NioEventLoop.<init>(NioEventLoop.java:120)
	at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:87)
	at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:57)
	... 16 more
Caused by: java.io.IOException: Unable to establish loopback connection
	at sun.nio.ch.PipeImpl$Initializer.run(Unknown Source)
	at sun.nio.ch.PipeImpl$Initializer.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.nio.ch.PipeImpl.<init>(Unknown Source)
	at sun.nio.ch.SelectorProviderImpl.openPipe(Unknown Source)
	at java.nio.channels.Pipe.open(Unknown Source)
	at sun.nio.ch.WindowsSelectorImpl.<init>(Unknown Source)
	at sun.nio.ch.WindowsSelectorProvider.openSelector(Unknown Source)
	at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:126)
	... 19 more
Caused by: java.net.SocketException: Permission denied: connect
	at sun.nio.ch.Net.connect0(Native Method)
	at sun.nio.ch.Net.connect(Unknown Source)
	at sun.nio.ch.Net.connect(Unknown Source)
	at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
	at java.nio.channels.SocketChannel.open(Unknown Source)
	... 28 more


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

-- Head --
Stacktrace:
	at net.minecraft.server.MinecraftServer.<init>(SourceFile:114)
	at bsk.<init>(SourceFile:38)

-- Starting integrated server --
Details:
	Level ID: New World-
	Level Name: New World
Stacktrace:
	at azd.a(SourceFile:1591)
	at bbi.a(SourceFile:202)
	at bcd.a(SourceFile:172)
	at bbi.a(SourceFile:301)
	at bcd.d(SourceFile:236)
	at bcd.k(SourceFile:211)

-- Affected screen --
Details:
	Screen name: btj
Stacktrace:
	at azd.o(SourceFile:1303)
	at azd.ad(SourceFile:753)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_05, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 215146224 bytes (205 MB) / 261160960 bytes (249 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -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: 1.7.2
	LWJGL: 2.9.0
	OpenGL: AMD Radeon(TM) HD 6520G     GL version 4.1.10600 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
	Anisotropic Filtering: Off (1)

Uninstall McAffee or Avast (or any other) antivirus

I have the same problem, and because of you I uninstall my anti-virus. Through the fault of this ridiculous and dangerous advice, I had a lot of problems, and the worst is that it has NOTHING changed my problem for Minecraft. I also updated my graphics drivers but it still does not work. What énnerve me the most is that you classify this as "resolved" after telling people to uninstall their antivirus. Do you realize?

MC-34749 is not resolved.