I am using Fedora 9 with below configuration:
Intel Core 2 Duo 2.33Ghz
XFX 650i Ultra mobo
XFX 8600 GT graphics card.
Dell SE 198WFP Monitor (Wide Screen)

Previously after installing fedora 9 it was not booting into GUI.To solve it i installed the nvidia drivers and new kernel.After that i was able to boot into GUI.But the new problem is that system freezes completely while working.Somebody suggested a problem with graphics card / refresh rate.

When i check my display settings it always shows the monitor type as LCD 1440 x 900 But when i try to change my resolution iam not getting the option of my native resolution i.e. 1440 x 900.Iam using a Dell SE 198WFP monitor.When i try selecting that monitor from display settings it says that the settings have been changed and ask me restart X server.But when i reboot and after i select the user and enter the password it just shows that default background screen of fedora.Then i had to go to command mode, start system-config-display and select the resolution as 800 x 600 and restart to work again. iam attaching my current xorg.conf file.You can note that the monitor type is still showing LCD 1440 x 900

Xorg.conf:
================================================== ==============================
# Xorg configuration created by system-config-display

Section "ServerLayout"
Identifier "single head configuration"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"
ModulePath "/usr/lib/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib/xorg/modules"
EndSection

Section "ServerFlags"
Option "AIGLX" "on"
EndSection

Section "InputDevice"

# keyboard added by rhpxl
Identifier "Keyboard0"
Driver "kbd"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
EndSection

Section "Monitor"
Identifier "Monitor0"
ModelName "LCD Panel 1440x900"
HorizSync 31.5 - 56.0
VertRefresh 56.0 - 65.0
Option "dpms"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
Option "AddARGBGLXVisuals" "True"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
Modes "800x600" "640x480"
EndSubSection
EndSection

Section "Extensions"
Option "Composite" "Enable"
EndSection
************************************************** ******

Can anybody help me?

If your xorg.conf works, then suddenly the computer freezes, my first suspect wouldn't be xorg.conf. Usually it won't start to work then crash, if there is a problem, in my experience so far, it just wouldn't start altogether. xorg has been pretty good at getting the correct refresh rate.

Are you doing anything heavy duty when it crashes ? Downloading updates ? Using yum ? Processing video ? An overheating cpu or gpu is usually my first suspect.

Hardware is usually my first guess. Can you boot and use knoppix, DSL or my favorite live distro, puppy ? If you can boot one of them, you can check their xorg.conf, and see if it crashes too. Make sure you aren't stressing the cpu when you run the test.

Let us know how it goes....

David

P.S. You might want to change the "screen" portion of your xorg.conf to the 1440x900 that you want, as it's now at 800x600.

# Xorg configuration created by system-config-display

Section "ServerLayout"
Identifier "single head configuration"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"
ModulePath "/usr/lib/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib/xorg/modules"
EndSection

Section "ServerFlags"
Option "AIGLX" "on"
EndSection

Section "InputDevice"

# keyboard added by rhpxl
Identifier "Keyboard0"
Driver "kbd"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
EndSection

Section "Monitor"
Identifier "Monitor0"
ModelName "LCD Panel 1440x900"
HorizSync 31.5 - 56.0
VertRefresh 56.0 - 65.0
Option "dpms"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
Option "AddARGBGLXVisuals" "True"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
Modes "1440x900" "800x600" "640x480"
EndSubSection
EndSection

Section "Extensions"
Option "Composite" "Enable"
EndSection
************************************************** ******

As far i can remember i was not doing anything heavy.Iam using dual boot with Windows XP and i don't have any problem in XP.Usually while using firefox or even while using terminal it just freezes.Neither the keyboard nor mouse works.Then i have to do a hard re-boot on the machine.Also, i changed the display settings using the nvidia configuration menu.