Help with new monitor

[Russell Blau]

I have Ubuntu (Hoary) installed on an Intel 486DX2 box.  I have two
computers (the Ubuntu box and a Windows box) sharing a keyboard, mouse, and
monitor using a KVM switch.

This weekend I installed a new LCD monitor.  It works fine with the Windows
box.  When I switch to Ubuntu I see the boot process just fine (in text
mode), but then when Gnome kicks in for the login screen the monitor goes
blank and I see "Cannot display current graphics mode."  So, the only way I
can get into Ubuntu now is by SSH'ing to it from another machine.

Here's the question -- somewhere on my system there is probably a file that
tells Gnome what the default graphics mode should be.  How do I find and
change that file to put in some plain-vanilla graphics mode that my new
monitor should be able to handle?

Thanks in advance.

Russ Blau