Coming back after about a week to say i found a solution (more of a workaround if anything). The crashing only happens if the game is rendering the world when I tab back. If I pull up a full screen in-game window, I have no crashes when I head back. So far, this is only the Enhancements "Manage" window, but it works, and prevents crashes.
Switched to windowed and i still have the same issue, unfortunately. I thought it might be a CPU priority issue, but after testing it on higher priority, it doesn't seem to fix it either
CoH will crash if I alt tab away from the game for more than a few seconds. This doesn't happen until I actually load into the world. Screenshot of my graphics settings attached.