Can't get to install screen

[Uni15]

System - GIGABYTE GA-EX58-UD3R
CPU - Intel Core i7-920
Graphics - Radeon HD 4870

I'm trying to install Mountain Lion but I can only get as far as the white screen with the apple and the loading circle under it before my screen goes black and says No Signal.
Please help.

 

[Mikhail716]

try booting with GraphicsEnabler=No -v

 

[Uni15]

try booting with GraphicsEnabler=No -v

Thanks, that worked!