Your logs won't be helpful then, the one from his side would be needed.

In the meantime, I suspect he is suffering from XACT errors, so please have a look at the relevant FAQ.

looks like your playing the campaign, some of the missions of the capaign have unit restrictions, dont ask me why like for story or some shit, but no theres no option to turn them back on again, although there may be a mod for it, and the part about the AA missiles, the discription does say both AA and sam missiles wich are the same thing.