"Rockstar: If game freezes, erase game data and start over
According to a chap over at the US PlayStation forums, a Rockstar has said that those who are experiencing problems with GTA IV freezing should "erase the game data (the original install and the game saves) and then start over." This apparently solves the issue."
Source :
MAXCONSOLE
En gros si ya des freezes supprimé la parti qui est installé sur votre console et réinstallé le jeux, et tout reviendra dans l'ordre.