While Take Two must be working overtime to try to fix the problems that are haunting the PS3 version of GTA IV for some people, there’s another temporary solution that may do the trick.

According to PSU, one trick may be to simply sign out of the PlayStation Network prior to booting up.

Here’s their "somewhat guarantee" about the trick:

I can at least somewhat guarantee the success of this method. I was plagued by an endless loading screens upon booting up the game, and I tried everything to remedy the situation - reinstalling the game, deleting the most recent save (out of two), swapping GTA IV discs, playing the game on a separate profile and so on. Nothing worked. Then I signed out of PSN and began the title, and viola, Niko stood amidst the denizens of Liberty City!

Take Two has also released a patch for the PS3 version of the game, but it appears for some people the problem still persists. The best thing to do is to sign in to the PSN from within GTA 4, not prior to loading up this seems to work best.