Pressed 'play' in new launcher. Loads up the 'Mojang' splash, but then gives this report:
---- Minecraft Crash Report ----
// Why is it breaking

Time: 01/05/13 15:09
Description: Failed to start game

java.lang.NullPointerException
at java.io.Reader.<init>(Unknown Source)
at java.io.InputStreamReader.<init>(Unknown Source)
at br.a(SourceFile:65)
at br.a(SourceFile:101)
at ask.K(SourceFile:311)
at ask.c(SourceFile:511)
at net.minecraft.client.main.Main.main(SourceFile:78)

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

– System Details –
Details:
Minecraft Version: 13w17a
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_03, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 88482768 bytes (84 MB) / 159645696 bytes (152 MB) up to 954466304 bytes (910 MB)
JVM Flags: 1 total; -Xmx1G
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
LWJGL: 2.9.0
OpenGL: AMD Radeon HD 7450 GL version 4.2.12002 Compatibility Profile Context 9.12.0.0, ATI Technologies Inc.
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Texture Pack: Default
Profiler Position: N/A (disabled)
Vec3 Pool Size: ~_ERROR~ NullPointerException: null

Resetting did not fix.