I have a new monitor and the native resolution is 1920x1080. My old monitor was 1600x900. I always ran the high res patch at 1280x720 and it worked out well. With the new monitor that resolution is stretched and there are black boxes above and below the picture. If I rerun the patch and select the native 1920x1080 it looks fine, but it is really small and I don't want the spoilers of seeing more of the map than what was intended. Any idea why I can't get 1280x720 to work right? Thanks

Check if your new monitor has built-in scaling options. Sometimes these can override the behavior for scaling up lower resolutions to fit your screen. This is assuming that nothing else about your system has changed besides the monitor. You can also double check your graphics card scaling options.

I went to the Nvidia control panel, and switched the scaling to "GPU" instead of "Display" - it seems to have worked

Excellent! Yeah, sounds like your new monitor has a weird way of doing scaling, but your graphics card can override that. Glad you got it working!