ArmA II / OA Installation problems

[ArmA II / OA Installation problems]

I just installed ArmA 2 and Operation Arrowhead from the Steam store. When I attempt to launch them, they both come up with errors preventing launch:

ArmA 2:

"Data file too short 'c:\program files(x86)\steam\steamapps\common\arma 2\addons.pbo'.

Expected 853343647 B, got 660602880 B"

Operation Arrowhead:

"No entry 'bin\config.bin/CfgInGameUI/MPTable.shadow'."

and

"Data file too short 'c:\program files(x86)\steam\steamapps\common\arma 2\addons.pbo'.

Expected 853343647 B, got 660602880 B"

If anyone is familiar with how to resolve these issues, help would be greatly appreciated.

Got the same problem here, already tryied deleting the Addons folder, checking the game cache, launching straight from the launcher, but nothing works.