I don't know what airline you are trying to install, but there might be a chance the airline you are trying to install may be one of the croupted files done way back when Avsim was hacked! You DID take the installer out of the zip file correct...?? Just asking....
Maybe try another airline......BTW....I have almost the entire WOAI installed and have had no problems......again it may be a corrupted file.......
Cheers,
Doug