OA Startup Error

[Chronos777]

I just finished installing ArmA 2: OA and had started it up. It pulls up the checkboxes that it likes to run through, and stops two boxes away from being complete. Then, it pulls up this error: "Data file too short: C:\Program Files\Steam\SteamApps\Common\ArmA 2\addons\air.pbo. Expected 120178246 B, got 32112640 B." I have restarted Steam, verified the cache multiple times, and rebooted the computer twice. Any other suggestions on how to get it to run?

Computer Specs: Windows XP SP 3 Home Edition (leave me alone, I didn't have the money for 7)
Intel Pentium Dual Core 3.60 Ghz, 3.37 GB RAM, GeForce GT 520 version 296.10

[Placebo]

Exit Steam, disable any antivirus, set steam to always run as admin: http://img717.imageshack.us/img717/5892/steamadmin2.jpg launch steam, verify cache integrity, reboot, launch steam.

[ProjectNorthland]

Ive tried that multiple times hasn't made any difference

[Bates]

Try browse to where Air.pbo is and delete it, then verify cache with Steam again. It should re-download that .pbo correctly.