When I go to any of my minecraft vanilla versions and press play on those versions, the launcher shows a "Game output(Username)" slot next to the profile editor..but when I click that slot it just shows a blank white screen and minecraft doesn't load no matter how many times I tried...The reason why this is in the modded client support is because I have been downloading mods and not sure if the mods were responsible for it but I do have the launcher log and wasn't able to find the crash log but however hopefully this log will help you guys..please help
Launcher log: http://pastebin.com/t9pCcKjt