Fail to run startx

[azizi_hooshang]

Dear friends,
I have installed ScientificLinux 5.0 .
When I run startx to switch to graphical mode, the following error appears and it doesn't switch:

Fatal server error:
no screens found
XIO: Fatal IOnerror 104 (Connection reset by peer) on X server ":0.0"
after 0 requests (0 known processed) with 0 events remaining.

Also, I copy errors and warnings of the Xorg.0 at the end of message.
I appreciate you to help me.
By the way, I'm a new user on linux and start to learn it.
My notebook specifications:
Dell 1558,
CPU: 2.27 core i5
RAM: 4 G
HDD: 400 G
VGA: ATI 512 M


Regards,
Hooshang.



X Window System Version 7.1.1
Release Date: 12 May 2006
X Protocol Version 11, Revision 0, Release 7.1.1
Build Operating System: Linux 2.6.18-8.1.1.el5xen i686 Red Hat, Inc.
Current Operating System: Linux localhost.localdomain 2.6.18-8.1.3.el5 #1 SMP Mon Apr 30 14:15:37 EDT 2007 i686
Build Date: 03 April 2007
Build ID: xorg-x11-server 1.1.1-48.13.0.1.el5
Before reporting problems, check wiki.x.org
to make sure that you have the latest version.
Module Loader present
Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Tue Jul 13 02:47:00 2010
(==) Using config file: "/etc/X11/xorg.conf"
(==) ServerLayout "Default Layout"
(**) |-->Screen "Screen0" (0)
(**) | |-->Monitor "<default monitor>"
(**) | |-->Device "Videocard0"
(WW) No monitor specified for screen "Screen0".
Using a default monitor configuration.
(**) |-->Input Device "Keyboard0"
(**) |-->Input Device "Synaptics"
(II) No default mouse found, adding one
(**) |-->Input Device "<default pointer>"
(WW) No FontPath specified. Using compiled-in default.
.
.
.
(II) VESA(0): Total Memory: 256 64KB banks (16384kB)
(II) VESA(0): <default monitor>: Using hsync value of 46.79 kHz
(II) VESA(0): <default monitor>: Using vrefresh value of 59.91 Hz
(WW) VESA(0): Unable to estimate virtual size
(II) VESA(0): Not using built-in mode "1024x768" (hsync out of range)
(II) VESA(0): Not using built-in mode "800x600" (hsync out of range)
(II) VESA(0): Not using built-in mode "640x480" (hsync out of range)
(II) VESA(0): Not using built-in mode "720x400" (hsync out of range)
(II) VESA(0): Not using built-in mode "640x350" (hsync out of range)
(II) VESA(0): Not using built-in mode "512x384" (hsync out of range)
(II) VESA(0): Not using built-in mode "320x240" (hsync out of range)
(II) VESA(0): Not using built-in mode "320x200" (hsync out of range)
(EE) VESA(0): No valid modes
(II) UnloadModule: "vesa"
(II) UnloadModule: "ddc"
(II) Unloading /usr/lib/xorg/modules/libddc.so
(II) UnloadModule: "int10"
(II) Unloading /usr/lib/xorg/modules/libint10.so
(II) UnloadModule: "vbe"
(II) Unloading /usr/lib/xorg/modules/libvbe.so
(EE) Screen(s) found, but none have a usable configuration.

Fatal server error:
no screens found[/COLOR]

[flipjargendy]

All I can think of is that something was configured wrong in your xorg file. Hopefully something that can easily be fixed by typeing:

dpkg-reconfigure xserver-xorg

into the command line when you are logged in as root.