It's the same window that opens when you right click the tray icon and select "Show Status". That window is titled "NextPVR Backend Status" and lists all the devices nextpvr has access to (like the HDHomerun Tuners). I often see it open on the the desktop when I haven't opened it. I figured it's part of the service startup and since I don't need to see the status unless there's a problem, I was wondering it I can prevent it from opening at when the nextpvr service starts up.
I don't have mine autostart, the web client shows me the status, but running it doesn't default to showing anything here which is why I asked. There are are lot of notification settings in Windows maybe one of them control this action?
You can disable the tray app from startup by going to Task Manager->Startup Apps.