For those of you that tried OP's solution but it didnt work (Like me) then this is how I did it. It might work for you. Make sure you have Arma 2's latest beta patch. Then, download Dayz's files BY TORRENT. This is way faster than downloading them manually, which takes forever and keeps on corrupting the files that took you 3 hours to download even with a 30mb/s connection. This is crap and needs to be fixed, so for now use the TORRENT which goes at 1.5 Mb/s. Go in your Arma 2 Operation Arrowhead folder in Steam/steamapps. Go in the @Dayz Folder, back up all of its content. Then delete all the content that is in this folder. Extract the .rar that you got from the torrent and copy over the folder "addons" that is in the extracted folders. Just the addons folder. Copy it. Paste the addons folder in your @Dayz folder that you have opened. Now go back to the main folder of Operation arrowhead. Go into Expansion,Beta and copy the exe thats in there (Not the one with "server" in it, the other one). Go back to the main folder of Operation Arrowhead and paste it there. IF it asks to replace say yes or back up the old exe. Go in your steam's library and right click on operation arrowhead. Click properties. Then under the general tab, click Set Launch Options. Paste everything here without the quotes "-beta=Expansion\beta;Expansion\beta\Expansion -nosplash -mod=@Dayz". Click ok and close everything. Now to launch the game, DO NOT use Sixupdater. Just go in your library of steam, right lick Operation arrowhead and click Launch Combined Operations. Thats it, here you go. Now, I do not know if the actual Sixupdater / Sixlauncher is all messed up and needs to be fixed, or if it is just the Dayz files that get corrupted. I do not know whats causing the problem, but until I did EXACTLY all of these steps listed above, nothing was wroking. Reinstalling wasnt fixing the issue, at all. But this did the trick. I hope I helped all of you.