This is one of the reasons why it's not a good idea to try and use a TV as a replacement monitor. My guess is that the Ubuntu installer tried setting a resolution that your TV can't handle, and so it gave an error.
With so few details about the system to work with: Try installing Ubuntu with an actual monitor, and then set the resolution to the native resolution of your TV.
So I have a PC loaded with ubuntu that I hook up to my flat screen tv. I decided to upgrade to the newest version of ubuntu, as I was installing the new version of ubuntu the tv just stops giving a display and says no signal detected. I'm not sure why since it was just working and the only thing I was selected was to install from disk. The install hadn't started yet either because it was at the screen where it asks if i have enough space, etc... I also decided to check the issue out and told it to load from disk and only let me try ubuntu without installing. Once it finally loaded I went to check the system settings and then the tv cut out again. I would appreciate any help you can offer thanks.