If you're trying to watch live \tv from the guide, you can just hit play rather than go through the menus. Play will start live TV if the selected show is currently playing. So anywhere you would have the watch option you can just hit play instead without going through the menus.
WIN 7
1 X PVR 250
1 X PVR 500
1 X HD-PVR
2 X MVP
2 X PCH A100