Sorry to bug you mate. Don't worry, not your fault.
I managed to find the game configuration file.
It's an xml document, in Windows7 anyway.
LOCATION:
C:\Users\Dopey Mug\Documents\My Games\Far Cry 2\GamerProfile.xml
Changed value to Fullscreen="1"... simple 
<GamerProfile>
<SoundProfile MusicEnabled="1" MasterVolume="100" />
<RenderProfile MultiSampleMode="0" AlphaToCoverage="0" ResolutionX="1440" ResolutionY="900" Quality="optimal"
Fullscreen="0" Maximized="0" ForceWidescreen="0" WidescreenFOV="0" AspectRatio="0" VSync="0" RefreshRate="60" DisableMip0Loading="0" MaxDriverBufferedFrames="0" Platform="d3d9" ShowFPS="0" ClustersZPassMaxLOD="1" Brightness="1" Contrast="1" GammaRamp="0.995" GammaRampR="1" GammaRampG="1" GammaRampB="1" AllowAsynchShaderLoading="1">
Will let you know if the settings hold with trainer if I set it to read only after stabilising the game, which I have but I have to go out now. Report back soon
