This is some of the most infuriating behavior..
This game brings up the escape menu every 1-3 seconds after I exit the menu. No joysticks attached, nothing weird sticking on the keyboard, I have NEVER seen any game do anything like this.
I have two monitors set up. However, it doesn't matter which one is set as "primary Windows monitor" in Windows. The only thing that seems to fix it is to put it on the "primary DVI output" display output on my dual DVI nVidia card (ie. the one that's active on bootup for BIOS, etc). Nothing else fixes it: setting just one display up, changing the "secondary DVI" to "primary Windows monitor", etc.
So in other words, even when I have dual displays configured, I can drag the window open to the "primary DVI output" and it stops behaving this way. Regardless of whether or not that monitor is set up as the "primary Windows monitor".
So I can work around it, but god it was infuriating figuring that out.