You can be Alt Tabbing in and out of games, the screen resolution for games varies from that of the monitor depending on the ingame settings. The graphics memory is already full with the game and the gpu is as good as full under load, when you alt tab out of that, it can't flush out the contents of the vram to accommodate the windows screen, so the reduced resolutions for both.... and thus when you get back to the game it runs at low res.
I believe, the trainer ought to be runing before you start the game. that'll solve the problem.
Yeah but the trainer wont start untill the game starts.