I sent it to the Steam Community :

I just bought Arma III, I launched it and I have a LOT of problems with it

First :
After I launched the game, I had 2 error messages :
first : Problem occured when saving profile data. The file may be set to read-only or can be blocked by another instance of the game (e.g., dedicated server).
second : Exactly the same (so : Problem occured when saving profile data. The file may be set to read-only or can be blocked by another instance of the game (e.g., dedicated server).)

Second :
When I go in "Play" and "Multiplayer" I cant' press "No" to the bootcamp, I only can say "yes"

Third :
When i'm in game, I can't "Save and quit", if I press it, the game save and didn't quit the game

Forth :
When I try to change my settings (and in fact my commands) I CAN'T save it
It's ok when I left the command but when I'm back in game, the command reset and I can't resolve it.

Please help me, Maybe that's cuz I dl the game in my external disk ?

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After that, a really nice guy tried to help me

I tried to copy his files and tried a lot of things but nothing is fixed. {F25037}