I don't have anti-virus installed in my computer and I have just reformatted 4 days ago. I never had any problems with the trainer other than the options don't work right away. But they do work after presing the key like 5 times. Once they work, I turned it off right away once I don't need the cheat.
My only suggestion though is to have a sound that will make you aware that the trainer is working and off sound when you turn the trainer option off. As of the moment, I have to count how many times I press the key as to not leave the trainer running in the background with me not aware about it. If you miscount and leave the trainer option still on, the cheat option activated will always be on even if you already close the trainer.
Thats odd. I can hear the sound of turning cheat on\off(different sounds) But there is no changes in the game no mater how many times I turn it on\off