I'm using the Switch with a Samsung KS9800 television, and when docked and in sleep mode, the Switch keeps switching the HDMI input to its port for no reason.

So while watching regular television, the television will randomly switch to a black screen (because the Switch isn't on). Once it starts doing this, it won't stop even after I change the input back...eventually I had to disconnect the Switch's HDMI cable until I'm ready to use it.

It's the expected behavior of the television to automatically switch HDMI inputs when a device is powered on and that works with thre Switch as well, but not when the Switch is off or sleeping.