DRI is for Direct Rendering. I'm not sure what the 'I' stands for exactly. Some drivers, like nVidia drivers, implement DRI on their own (built in), but ATI does not, it uses X's DRI, so that is why that is there.
Now, first things first, I agree with Gethyn, above: If the console is funny right from bootup, you should look into the framebuffer settings, which are set using your bootloader (LILO or GRUB) and ALSO through the framebuffer configuration inside your kernel.
If you are running a generic kernel, it probably includes just about everything it might need, but the framebuffer might be configured less than optimally for your setup.
Seeing as how the other monitors you have seemed to work fine, I suspect the kernel is OK. It would be worth trying Gethyns suggestion, and trying a few different modes, and also try 'vga=normal' and see if that works.
As for your xorg.conf file, let's see..
1 - Change the Horiz and Vert rates to match the monitors specs exactly. This can make a difference in general functioning, despite that we are dealing with the console, not the X environment.
2 - Definitely look on Google for a Modeline calculator, or find a list of proper modelines, and make sure that your options for modelines are within the frequency ranges for your monitor. For example (and I'm no good with modelines
) the first number in a modeline represents a frequency, I believe. by looking at your 1280x1024 modeline, the frequency appears to be outside the range of your monitor. Again, don't quote me here, but it's worth looking into.
3 - Does this problem occur ONLY when LEAVING X and going to a console, and NOT during boot? If so, consider this: Your xorgf.conf file has no MODULES section. It's rare for this to be the case, as loaded modules can provide functionality that is otherwise missing from X. A typical MODULES section looks like this (from my own file):
# Load "vnc"
Two which you should particular be interested in are 'int10' and 'fbdevhw'. Int10 uses the Int10 BIOS call to instruct the video card to refresh when leaving the X environment, and fbdevhw is the "hardware framebuffer device' as opposed to the 'software' framebuffer which might be giving you troubles.
You may or may not need some or most or all of these modules, but check in the xorg.conf man page for more details on each one, and/or check the docs for your driver too.
Finally, adding a line like
Option "ConnectedMonitor" "DFP"
in the DEVICE section tells the X server that there is a digital flat panel monitor connected to the video card. It may help, or maybe not. Can't hurt to try it though. Other types are "CRT" and "TV" (and *maybe* "LCD" but I think DFP covers that).
I hope some of this helps you, or atleast leads you to some more information which may help too. Best of luck; keep us posted!