When you start WMC, if you are navigated down to TV if you push the "Recorded TV" icon you will see your list of recordings to choose from, and no "live TV" program will be playing at that moment.
If from the opening WMC screen (at TV) you navigate over and push the "Guide" icon you will see the Guide grid to navigate through, and no "live TV" program will be playing at that moment. If you navigate to a channel and push OK to watch that channel, it becomes the currently selected channel which will be what "Live TV" opens to if you use that method to launch from the main WMC opening screen.
Only from the opending WMC screen (at TV) if you navigate over and push the "Live TV" icon will you be immediately placed into viewing "live TV", and it should be the last channel you had previously been watching live. I would have though channel 31 was selected by as the last "live TV" channel you had been watchin.
So... how are you getting into WMC, with that channel 31 appears? Have you ever watched channel 31 yourself?