I installed ArmA2, ArmA2 OA and ArmA2 RFT in different directories:
1. C: \ Program Files \ Bohemia Interactive \ ArmA 2 \
2. C: \ Program Files \ Bohemia Interactive \ ArmA 2 Operation Arrowhead \
3. C: \ Program Files \ Bohemia Interactive \ ArmA 2 REINFORCEMENTS \
All ArmA 2 to version 1.11, ArmA 2 OA and ArmA 2 RFT to version 1.59 updated and run successfully.
Then ArmA 2 OA and ArmA 2 RFT successfully updated to version 1.60.
After this update ArmA 2 RFT run successfully. But when run ArmA 2 OA (!) then get a message "Failed to load file" C: \ Program Files \ Bohemia Interactive \ ArmA 2 REINFORCEMENTS \ BAF \ addons \ air_d_baf.pbo "- decryption of headers failed."
I reinstalled and updated both ArmA 2 OA and ArmA 2 RFT to version 1.60 but lead to the same effect.
I completely removed all the games. At the time I wanted to combine the ArmA 2 and ArmA 2 OA together into ArmA 2 CO. While I updated them in another way. I installed ArmA 2 then ArmA 2 OA into the single directory by default, and created ArmA 2 CO. Further I add ARMA 2: RFT DLCs with Setup Utility from site http://www.arma2.com (this function does not run on the original CD) and immediately updated this via the patches v1.60 then v1.62. Thus I have solved this problem!
Thanks Dwarden for the lightning-fast support !
PS: Since the problem exists, then decrypt the files it needs to be solved in the next update release.