Minecraft crashes while connecting to server

---- Minecraft Crash Report ----
// I bet Cylons wouldn't have this problem.

Time: 05/09/13 16:29
Description: Ticking screen

java.lang.NullPointerException
at java.net.URLEncoder.encode(Unknown Source)
at net.minecraft.src.NetClientHandler.urlEncode(NetCl ientHandler.java:162)
at net.minecraft.src.NetClientHandler.sendSessionRequ est(NetClientHandler.java:144)
at net.minecraft.src.NetClientHandler.handleServerAut hData(NetClientHandler.java:125)
at net.minecraft.src.Packet253ServerAuthData.processP acket(Packet253ServerAuthData.java:48)
at net.minecraft.src.TcpConnection.processReadPackets (TcpConnection.java:448)
at net.minecraft.src.NetClientHandler.processReadPack ets(NetClientHandler.java:107)
at net.minecraft.src.GuiConnecting.updateScreen(GuiCo nnecting.java:43)
at net.minecraft.src.Minecraft.runTick(Minecraft.java :1503)
at net.minecraft.src.Minecraft.runGameLoop(Minecraft. java:786)
at net.minecraft.src.Minecraft.func_99999_d(Minecraft .java:715)
at net.minecraft.client.main.Main.main(Main.java:92)
at Start.main(Start.java:11)


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

-- Head --
Stacktrace:
at java.net.URLEncoder.encode(Unknown Source)
at net.minecraft.src.NetClientHandler.urlEncode(NetCl ientHandler.java:162)
at net.minecraft.src.NetClientHandler.sendSessionRequ est(NetClientHandler.java:144)
at net.minecraft.src.NetClientHandler.handleServerAut hData(NetClientHandler.java:125)
at net.minecraft.src.Packet253ServerAuthData.processP acket(Packet253ServerAuthData.java:48)
at net.minecraft.src.TcpConnection.processReadPackets (TcpConnection.java:448)
at net.minecraft.src.NetClientHandler.processReadPack ets(NetClientHandler.java:107)
at net.minecraft.src.GuiConnecting.updateScreen(GuiCo nnecting.java:43)

-- Affected screen --
Details:
Screen name: net.minecraft.src.GuiConnecting
Stacktrace:
at net.minecraft.src.Minecraft.runTick(Minecraft.java :1503)
at net.minecraft.src.Minecraft.runGameLoop(Minecraft. java:786)
at net.minecraft.src.Minecraft.func_99999_d(Minecraft .java:715)
at net.minecraft.client.main.Main.main(Main.java:92)
at Start.main(Start.java:11)

-- System Details --
Details:
Minecraft Version: 1.6.2
Operating System: Windows 8 (amd64) version 6.2
Java Version: 1.7.0_21, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 978727280 bytes (933 MB) / 1038876672 bytes (990 MB) up to 1038876672 bytes (990 MB)
JVM Flags: 3 total; -Xincgc -Xmx1024M -Xms1024M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: Start[com.fiy.Variables, Loader, ClientHandler, ...], [com.fiy.gui.GuiClick], [net.minecraft.src.MainProxyAuthenticator, MainShutdownHook, IPlayerUsage, ...]
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: mcp
LWJGL: 2.9.0
OpenGL: Intel(R) HD Graphics 4000 GL version 4.0.0 - Build 9.17.10.2828, Intel
Is Modded: Very likely; Jar signature invalidated
Type: Client (map_client.txt)
Resource Pack: Default
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: ~~ERROR~~ NullPointerException: null