A couple points:
1) Your TV may be jumping to a different HDMI connection if it detects an issues. I DOUBT this is the problem, but verify that the HDMI input (i.e. "HDMI 1" matches the shown screen when it shows "no display.")
2) Clone mode:
If you are in CLONE mode (show same thing on both screens) you may have issues. You need to have completely different settings for each screen. i.e. Screen #1 (your laptop) is the MAIN screen and your HDTV is the EXTENDED.
3) Try changing your TV to the MAIN screen and have NO EXTENDED screen at all just to test if this is possible. If so, you'll see nothing on the laptop and the TV will be basically a monitor.
4) For HDTV you should use the "HDTV mode", if your TV support it you should be using 1080p@60 (North American standard for full 1920x1080 HDTV).
The fact that you initially see a screen on your HDTV tells me that it's a setting issue with one of the above.