when i press the play button on mine craft it freezes

so when i go to press the play button on mine craft it comes up with this
Launching game
Looking for old natives to clean up...
Fatal error launching game. Report this to http://mojang.atlassian.net please!
java.lang.NullPointerException
at net.minecraft.launcher.GameLauncher.cleanOldNatives(GameLauncher.java:515)
at net.minecraft.launcher.GameLauncher.launchGame(GameLauncher.java:360)
at net.minecraft.launcher.GameLauncher.onDownloadJobFinished(GameLauncher.java:693)
at net.minecraft.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:124)
at net.minecraft.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:15)
at net.minecraft.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:94)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)