I'm one of many unlucky souls that is currently experiencing the intermittent freezing issue with Grand Theft Auto IV on PlayStation 3. However most are reporting problems only with installation or in the very beginning of the game. My installation went smooth, but unfortunately I'm a good six hours into the game and it randomly locks up on me while in the middle of game play. The only thing I can do is hit the power button on my PS3 and start back from my last save.
Here's a YouTube video I made demonstrating the problem:
GTA 4 issue
Rockstar - please fix this quick!
My video was pulled for reasons I'm not sure of. I'm trying to find another way to host it.