this only works if you are able to log into your rockstar account, which many aren't and reporting MMA10 errors-
best,
Cal
Error Code MMA10
Cause: Rockstar Social Club
Solution: Simply log out of the Social Club before playing GTAIV. To sign out, click the "Log Out" button below your username int he Social Club window.
Notes: If you wish to play multiplayer, simply minimize GTAIV, log into the the Social Club, then maximize GTAIV once more. Multiplayer will work just fine.
Helpful thread with some of the errors: Link