you probably mean that you can't start your X server (the graphical system). Best thing you can do is edit /etc/X11/XF86Config-4 file. The part that needs to be edited is similar to this:

do you have this high resolution in x, well stupid question maybe, but that's my first guess

well you could try to reconfigure your XF86Config file or XOrg.conf and edit the section below

Subsection "Display"
Depth 8
Modes "1280x1024" "1024x768" "800x600" "640x480"
ViewPort 0 0
EndSubsection

you should also have these entries for 16/24/32 bits depth, just remove the modes that are too high or the ones that are too low also, i do not know anyone that is still using the 640x480 res on a home or normal work pc..
just restart your x and you might see some changes

Maqish

(edit) didn't see someone posted the same above me well that's what you should do

so, how then do i acces my terminal thing or my command prompt during the boot sequence. since i cannot acces my linux gui i cannot log out or anything. in the dual boot screen should i use c for command... well i just answered my own question.

well, you should use ctrl-alt-f6 as soon as the system is done booting.

a fresh command prompt should appear and you are able to logon using cli. edit the file and well restart should do the trick.

Maqish

if everything else fails you can usually use disk 1 of your installation disks as a rescue disk. boot up with the disk installed and there is usually some kind of recovery/emergency mode that will boot into a prompt, somtimes making an image to boot to and restoring this image when you exit.

in addition to lyceum,

when starting using disk 1, when asked to login u can mount your linux root partition, and edit the file that way..
or chroot /mnt/<linux root mountpoint>
and then edit the file, but that is not really needed..

Maqish

Euhm, don't want to critisise your boot disk but maybe for a noob it is easier of he doesn't have to mount anything.
Just boot without the disk, you pc will try to boot into X, but just let it go wrong. After a minute or something the screen stops blanking and goes back to a console. When I had problems with RH8, I could log on straight away, but I've noticed that this isn't the case in Slack so if you can log on on the command line, do it. Else, press CTRL+ALT+F6 and log on there (as root).
now you need an editor... euhm try
#> pico /etc/X11/XF86Config-4
if you don't have pico, try nano and if this doesn't work take vi. Vi is the hardest editor for a noob, but no doubt that will work. To edit the file you first have to press 'i', if you want to save the file press ':x', if you want to quit without saving, press ':q!'.
I recommend you to read the manual (command: 'man vi') before trying vi, it is quite a b*tch to tame .
If you edit that file, better first try some conservative resolutions like 800x600 with 8bit colors...
Once you edited the file, you don't have to reboot, just type
#> startx
if boot fails, it wasn't that resolution :S.

You can also change a config file so your pc won't boot in X, this can be usefull as long as things go wrong, you can change it back afterwards. Just edit a line in /etc/inittab:
id:5:initdefault:
to
id:3:initdefault:
this way your RH will stop at command line prompt.

lot's of luck,
elluva

well, i got it to work again.. i switched the res to 800 by 600, and at the generic monitor so that i could use it on my pc. but until then i have no problems.

euhm, is 800x600 the maximum it does? at least 1024x768 should be possible...