try lowering the graphics settings in the launcher menu
or try pressing the tilde key (the one above tab and below escape) and typing in "pcb" without the quotation marks every now and then, this clears the RAM of everything not currently in use and improves performance
Or set the PC's screensaver to a longer time. Most cases, when crashes occur after standing around a bit, the screensaver is trying to kick is as it's too dumb to realize you're running a game and may be reading or something that doesn't require hitting keys or moving the mouse. Set it for 1/2 hour or longer. Also, the power management may be trying to put the computer to sleep, check that too.
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