running Doom 3 with tv as monitor problem

[Face23785]

I'm trying to run Doom 3 on my laptop but hooked up to my tv as the monitor. I have done this with other games before, as well as watching movies etc, but Doom 3 keeps trying to run in a window. I have tried manually setting the screen resolution in the .cfg to match what the tv is set at, but it still keeps trying to run in a window. It's very annoying and I don't understand whats wrong. Can anyone help?

[Xeros612]

Does alt+enter work? Most programs I know of will plop the program into fullscreen using that.

[DeumReaper]

When you edit DoomConfig.cfg (seta r_customHeight/Width "x") do you also set seta r_mode to "-1" , also in config? It applies the custom res.
Also is seta r_fullscreen set to "1" as well?