It sounds like you are having the output routed through to the wrong connector.
Edit your /etc/X11/xorg.conf:
Option "TVStandard "xx"
For the VGA connector, xx=CRT
For SVideo connector, xx=TV
I'm not sure what DVI is, but if you are using DVI, reply to this and I'll look it up for you. Assuming you haven't already solved the problem, that is
I am using the DVI connector on a 7600. Think using DVI in the xorg.conf file would work? I guess if you know where to look something like this up that would be great! Thanks.
Option "TVStandard" "DFP"
You can also try in addition to the above line, to have a line which says
Option "UseDisplayDevice" "DFP"
What is the difference? TVStandard tells the card what is connected to the ports at the back of the card. UseDisplayDevice tells the driver which of the devices connected is the one to use, and is useful only when more than one device is plugged in.
Also check the following:
Replace any line which says Driver "xx" with:
Existing Driver options might be nv, vesa or fbdev. Whatever it is, replace it.
Under the Modules section, remove any lines that say Load "dri" or Load "glcore", and make sure you have
Let us know how you go. Good luck!