As you don't provide that much of information I suggest let Steam update your legally purchased game to the latest version and try our latest trainer. If you should still have issues the next step would be ...
Please disable/uninstall all antivirus, firewall and other security software including browser addons and extensions. Right click "Run as Administrator" on trainer and game. Please note that some security products may still block access to trainer injection even when disabled and must be completely uninstalled. If this is the case, please contact the product vendor for instruction on the proper way to prevent the trainers from being blocked by their software or find a better alternative.
Just to let you know, I just finished the game 2 days ago and the latest trainer worked fine.
TaurusPlopp's advice is almost certainly going to be exactly spot-on for you.
I had some of that when I loaded an older save. Didn't seem to happen if I continued a save point or current save, just when loading an older save back to a previous time.
Another member that was also playing suggested it happened to him when he had too many options activated and that did seem to somewhat affect it.
With me happens with any save, recent or old, but it only happens after a while playing, maybe 15-30mins? Plus i only have 1 option ON which is the endless mana. One thing i noticed is that the unlimited grenades/items cheat seems to be stuck on my save whenever the trainer is ON even when not activated. That maybe could be it. I only use the cheat 3 times then found out was not really necessarily and let go but it kinda auto-activates when the trainer is ON. When what i mean with auto-activates is not when you truly activate a cheat and hear "ACTIVATED" what i mean is, when the trainer is ON (F1) i turn on endless mana and disable hotkeys but when i go and use items they don't decrease and are stuck on 09 amount. And again, that only applies when the trainer is ON. Without it, items decrease as normal.
That's interesting as I'm almost positive it only crashed when loading an older save with me. I don't really think the number of options mattered a lot at least not for me. There were times when I unloaded the trainer using Ctrl + H but it didn't seem to matter.
It didn't happen too often, maybe once or sometimes twice during a 5 or 6 hour session. I never foramlly reported it because I couldn't nail down a solid reason to report, so I just finished the game as is and moved on.