Rockstar are still working on a fix for the GTA IV freezing issues but until a patch is available a temporary fix is available for you to try out. According to several reports, and from our own testing, we have found that most of the freezing issue can be resolved by simply signing out of the PlayStation Network before booting the game. However, this means that you will not be able to play any online multiplayer games until an official patch is available.
We’ve tested this method and it seemed to solve most of our freezing issues. If you later sign-in to the PlayStation Network, the game may crash instantly upon successful sign-in. Most GTA IV discs work fine with the PSN signed-in, but others don’t. Let us know if this method worked for you using the comments section below.