FWIW, I never leave a session open for more than 5-10 minutes. My rig is completely different than yours but I still had similar experience. Now, whenever I am going to be away, I save and close the session(leaving PT open). Never had an issue since
BTW, you don't need to turn the monitor off as flatscreens do not suffer screen burn like the old CRT;s did. Turning the screen off is confusing your graphics processor, hence the screen resolution change
