When I try to play, the launcher downloads the 1.7.4 version but when finished, the game doesn't run. The development console show an error: the last entry is "[18:01:58 INFO]: Unpacking natives to C:\Users\Benjamin\AppData\Roaming\.minecraft\versions\1.7.4\1.7.4-natives-2324579324716
[18:01:58 ERROR]: Couldn't unpack natives!
java.util.zip.ZipException: error in opening zip file
at java.util.zip.ZipFile.open(Native Method) ~[?:1.7.0_45]
at java.util.zip.ZipFile.<init>(Unknown Source) ~[?:1.7.0_45]
at java.util.zip.ZipFile.<init>(Unknown Source) ~[?:1.7.0_45]
at java.util.zip.ZipFile.<init>(Unknown Source) ~[?:1.7.0_45]
at net.minecraft.launcher.GameLauncher.unpackNatives(GameLauncher.java:469) ~[launcher.jar:?]
at net.minecraft.launcher.GameLauncher.launchGame(GameLauncher.java:213) [launcher.jar:?]
at net.minecraft.launcher.GameLauncher.onDownloadJobFinished(GameLauncher.java:619) [launcher.jar:?]
at net.minecraft.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:120) [launcher.jar:?]
at net.minecraft.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:12) [launcher.jar:?]
at net.minecraft.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:89) [launcher.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_45]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.7.0_45]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.7.0_45]
at java.lang.Thread.run(Unknown Source) [?:1.7.0_45]
"

What I expected to happen was...:
download the game normally

What actually happened was...:
The game haven't been fully download and installed

Steps to Reproduce:
1. If In knew how to reproduce it, I would know how to fix it!
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