GTA 5 won't install without Windows Media Player, it seems. 'Unable to detect Windows Media Player' issue Repeated tries can get you in, but it's not likely to ease off until the demand reduces or Rockstar bolsters the system. If that doesn't fix it it seems that Social Club is struggling with launch demand. Press the Home key and see if you can log in manually.' Rockstar's advice: 'If you are stuck loading, auto-signin may have failed. Rockstar also recommends running the game as administrator (right click Social Club, choose 'Run as Administrator') and checking that the Social Club is installed in the right place-Program Files\Rockstar Games\Social Club.

If you have the Steam edition, verifying the game cache can help-right click the game in Steam, go to properties, hit the local files tab and click the verify integrity of game cache button.

If you are receiving one of these errors, we recommend uninstalling Social Club and then reinstalling it manually from this page.' Rockstar's says: 'The most common cause for these errors is an incorrect installation of Social Club.