Launcher is unable to unpack natives because they are in use by another process

I tried to launch minecraft from the new launcher and i got this,
Launcher started...
Getting syncinfo for selected version
Queueing downloads
Launching game
Couldn't unpack natives!
java.io.FileNotFoundException: C:\Users\Noah\AppData\Roaming\.minecraft\versions\13w16a\13w16a-natives\lwjgl64.dll (The process cannot access the file because it is being used by another process)

Also there is no(known)way to allocate more ram for this update, so Some times I have to delete screen caps and saves, so the updated launcher will launch.