I've seen similar issues reported here, but the more details that are provided, the faster the problem will be fixed. This bug has happened to me twice since November 22nd. I have found a temporary fix, until a patch is released.
The Problem (or Bug): TV app (and TV Settings app) stops working unexplainably on the next system startup. TV app was working as designed before the next startup.
Associated Issues: The TV and AV Receiver QUIT Turning On and Off with the system, but this worked fine before the problem occured. TV and Receiver quit Turning Off with the system on the last Shut Down prior to the problem. Since TV Settings app toggles this function on/off, I believe the Settings Application crashing could be part of the problem.
Possible Issues (Could be associated): Dish Network Hopper box (HDMI IN to the xbox) has never Turned Off when the rest of the equipment automatically turned off. This could be by design, but I reported it in case it is related. My Power Supply box always has a White Light on, even when the xbox is off. I'm not sure if this is supposed to be yellow or red when the xbox is off, or if this is by design.
Error Message Received: When Launching the TV app (or TV Settings), a black screen with the TV logo is displayed. After less than a minute of waiting, an error message is displayed, "Please try again. For some reason TV took too long to start. (0x8027025a)
Xbox Power Settings: Instant-On Power. Automatically Turn On and Off everything (TV, Receiver, and set top box).
My Home Theater Setup: Dish Network Hopper box from 2013 (HDMI In to Xbox), Yamaha RXV673 Receiver (HDMI Out from Xbox), and Samsung 52" LCD TV from 2009 (HDMI Out from Receiver)
My Theory on the problem: I am unsure of the cause of this problem, but I believe the glitch happens when Turning Off the Xbox. I have heard rumor that it affects Instant On Power mode, but have not tested this.
Step-by-step explanation of what happened in my case (Case 1): TV was working fine on Saturday night (I had rebooted several times between Thursday and Saturday night with no issues), until the problem occurred wihout reason on Saturday night around 1 AM EST. I held down the Xbox button on the controller and turned off the system. No other equipment turned off with the Xbox (it normally does when using voice or the controller). I manually turned off my equipment and went to bed. The next morning, I said "Xbox On". The Xbox came on, but the rest of the equipment did not turn on. I said "Xbox Watch TV", and that's when the problem first occurred. I tried to access TV Settings with the controller, but I had the same problem. I tried rebooting the system (without unplugging it) and disconnecting & reconnecting the HDMI cable; but nothing helped. I ended up Restoring Factory Defaults, which fixed the problem... but I had to reinstall & redownload everything. What a long process!!
Step-by-step explanation of what happened in my case (Case 2): TV was working fine on Sunday and Monday (I had rebooted several times in this time frame without issues), but the problem suddenly occurred without reason on Monday night around 11:30 PM EST. I had done nothing different than usual. I said "Xbox Turn Off" > "Yes". The Xbox turned off, but the rest of my equipment did not turn off. I manually turned off my equipment; but I immediately knew that the same problem had occurred again. I said "Xbox On", and sure enough.. the problem happened again! No TV App, No Automatically Turning on my TV or Receiver. I refused to Restore Factory Defaults again for this to happen again. I unplugged the power cable going to the power supply, waited 10 seconds, and plugged it back in. I touched the "X" on the Xbox console to turn it on. The TV and Receiver turned on automatically this time, so I knew it was working. Sure enough, the TV app was working again. I could also access the TV Settings App again.
Temporary Fix (until Official fix is made): Unplug the Power cord to the Power Supply (or from the wall). Wait 10 seconds (enough for capacitors to discharge), and plug it back in.
Please fix this soon Microsoft!! I've seen reports of this from several folks on the forum. This is a CRITICAL component to your Xbox One sales, as this "One box" idea is the #1 selling feature to non-gamers and very casual gamers.