There is some weird BEX64 exception (on GTA5.exe) or buffer overflow that happens with the ammo options (Infinite Ammo and No Reload) and drive by shooting. I ended up glitching into it by apparently having too much ammo after filling up at the gun store, jumping into a car, and attempting to fire a gun. It wasn't always the first car I got into, but without fail, by two or three cars in, it would immediately crash to desktop. It may be one specific gun, it is hard to tell, I only have the 4 you can buy at the very beginning, but I think it is one of the automatics. I always seemed to have the large automatic equipped when getting into the car, but you can't shoot that one out the car window.
I believe I was maybe able to fix my game by disabling the two options and firing off a few clips. Then the options seemed to work again without crashing me.
This game takes so long to load into, trial and error on a crash is a bit of a pain. Is anyone else having similar issues while driving, shooting, and using the trainer?
I don't think its the trainer. Try doing what your doing without the trainer running. If your computer takes a long time to load into, it might just be your computer.
I have a high end PC(Top of the range cant even upgrade anymore to get any more FPS) and I have no issues.
My friend has a similar issue, he is using pretty bad laptop and it takes him about 10 minutes to get in game. After about 15 minutes of doing a lot of GPU and CPU heavy things in game like shooting blowing up things his game crashes, sometimes even his PC.