Change monitor, out of range issue
 

I have been using a REDHAT machine on a CRT monitor and now I just replace it with a new LCD. However, when I boot it, it says the resolution is "out of range". What do I need to do to make this machine with with my LCD monitor?

You probably need to modify the "monitor" section of the xorg.conf file to contain the new resolution, vert & horiz sync, etc.

how do I modify it in the first place? it is now booting on LCD monitor, but I cannot see anything on the screen.

Try hitting CTRL+ALT+F1 to get to a shell. Then login and use your favorite command line editor (vi, emacs, nano, etc).