[bobones]

Also, I get same 1/4 screen xbmc as raymw when trying 1080p output.

Throw away; GUISettings.xml or at least the resolution section within that file.

Thanks j1nx. That works!

Pity I only have a 720p TV so I can't check if it's true 1080p with the test videos.

@raymw

The file is in /root/.xbmc/usersettings

I edited mine by logging on with ssh (putty for windows), stopping xbmc (/etc/init.d/xbmc stop), edit with text editor (vi or nano) and removed all resolution settings, started xbmc again (/etc/init.d/xbmc start). You could also just rename your guisettings file and start xbmc with no file.