Looking at the log I personally can't see anything that is possible causing the crash. The only thing I can think of is that when you have mods installed in GTAIV is that it is really quite unstable and that maybe one of the things that you have changed recently has caused the game to crash more frequently. Try removing the things that you have added and reverting any setting changes that you have made and see if that helps. I'm sorry if I have been a complete waste of your time. I can usually spot these things pretty quickly.