Planet Minecraft

whenever i go into ht launcher and click "login" it goes blank then the login "mojang" logo for ages and then has an error report so how do i fix this i have tried restarting my computer and force updating but it dosen't work!?

heres what it says




Minecraft has crashed!
----------------------

Minecraft has stopped running because it encountered a problem.




--- BEGIN ERROR REPORT 7cf3a456 --------
Generated 30/06/12 10:53 PM

Minecraft: Minecraft 1.2.5
OS: Windows 7 (x86) version 6.1
Java: 1.7.0_04, Oracle Corporation
VM: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
LWJGL: 2.4.2
OpenGL: ATI Mobility Radeon HD 5470 version 4.0.9901 Compatibility Profile Context, ATI Technologies Inc.

java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:78)
at java.io.InputStreamReader.<init>(InputStreamReader.java:97)
at adn.a(SourceFile:62)
at adn.a(SourceFile:99)
at net.minecraft.client.Minecraft.a(SourceFile:262)
at net.minecraft.client.Minecraft.run(SourceFile:657)
at java.lang.Thread.run(Thread.java:722)
--- END ERROR REPORT 20c50b49 ----------

you screwed up your Minecraft.jar
OR
Your computer is using too mush RAM currently
OR
Your computer can't run MC
OR
Your computer is for some reason not finishing the tasks required to run Mc

ive been playing it since 1.7.3 and it only stuffed up after i took out the 12w26a snapshot file

[sed11]

1.Delete your whole .minecraft folder.

2.Delete your minecraft launcher.

3.Restart computer (It might help.)

4.Re-download the minecraft launcher at minecraft.net.

5.Enter your username and password in launcher then log-in.

And if this doesn't work, just play the browser version if you're not using mods.

Pull up your minecraft, go to options under login.Click force update, then login. Hopefully this works, if not, do what sed11 says.