Jerrett Rowley

Having the same issue. Here are the details the console gave me.

Launcher 1.0.7 (through bootstrap 4) started on windows...
System.getProperty('os.name') == 'Windows 7'
System.getProperty('os.version') == '6.1'
System.getProperty('os.arch') == 'x86'
System.getProperty('java.version') == '1.7.0_25'
System.getProperty('java.vendor') == 'Oracle Corporation'
Going to log in with legacy stored username & password...
Loaded 2 profile(s); selected '(Default)'
Trying to log in...
Logging in with access token
Logged in successfully
Delta time to compare resources: 1959 ms 
Download job 'Resources' skipped as there are no files to download
Job 'Resources' finished successfully
Getting syncinfo for selected version
Queueing library & version downloads
Download job 'Version & Libraries' started (8 threads, 1 files)
Finished downloading C:\Users\user\AppData\Roaming\.minecraft\versions\1.6.1\1.6.1.jar for job 'Version & Libraries': Used own copy as it matched etag
Job 'Version & Libraries' finished successfully
Launching game
Looking for old natives to clean up...
Unpacking natives to C:\Users\user\AppData\Roaming\.minecraft\versions\1.6.1\1.6.1-natives-344584242220
Launching in C:\Users\user\AppData\Roaming\.minecraft
Running C:\Program Files\Java\jre7\bin\javaw.exe -Xmx1G -Djava.library.path=C:\Users\user\AppData\Roaming\.minecraft\versions\1.6.1\1.6.1-natives-344584242220 -cp C:\Users\user\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.0\lwjgl-2.9.0.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.0\lwjgl_util-2.9.0.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\argo\argo\2.25_fixed\argo-2.25_fixed.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\org\bouncycastle\bcprov-jdk15on\1.47\bcprov-jdk15on-1.47.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\14.0\guava-14.0.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;C:\Users\user\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.2\gson-2.2.2.jar;C:\Users\user\AppData\Roaming\.minecraft\versions\1.6.1\1.6.1.jar net.minecraft.client.main.Main --username cyric47 --session token:02a813f23d604b10a31da47977bc7f5b:eddbb9ea222b49248a0543dd02257101 --version 1.6.1 --gameDir C:\Users\user\AppData\Roaming\.minecraft --assetsDir C:\Users\Jerrett\AppData\Roaming\.minecraft\assets
---- YOU CAN CLOSE THIS LAUNCHER IF THE GAME STARTED OK ----
---- YOU CAN CLOSE THIS LAUNCHER IF THE GAME STARTED OK ----
---- YOU CAN CLOSE THIS LAUNCHER IF THE GAME STARTED OK ----
---- (We'll do this automatically later ;D) ----
Game ended with bad state (exit code -1073740777)
Deleting C:\Users\user\AppData\Roaming\.minecraft\versions\1.6.1\1.6.1-natives-344584242220

Hope you guys can come up with a fix soon. As per the others in this thread, I can access 1.5.2 and earlier snaps fine, but 1.6 fails to load.