[Preston] Monitor setting

[Matthew Field]

Hello all

Hoping some body can help me. I tried to install RH9 on a box, but got
the monitor resolution / refresh wrong. Now when I try to boot it the
monitor just rolls over and says "Frequency Over Range" . 

I'm assuming that there is a config file that could be changed to sort
this out? I've booted the box with Knoppix and found /etc/X11/XF86Config
but can't modify it or change permissions from Knoppix. Is this the
right file? 

I presume that to modify it I'll need to tell grub to boot the box to a
command line? How? Can anybody point me towards anything on the web that
deals with this problem?

Cheers

Matthew Field