Well. Again problems with nvidia drivers.
After fresh copy of Xubuntu installation, decided to install nvidia drivers immediately.
First of all uncommented
#deb http://lv.archive.ubuntu.com/ubuntu dapper universe
in sources.list.
Then did
udo apt-get install nvidia-glx nvidia-kernel-common
it asked me to write password. And so I did it.
After that ran
sudo nvidia-glx-config enable
which said the following:
zivs@zivs:~$ sudo nvidia-glx-config enable
Password:

Error: your X configuration has been altered.
This script cannot proceed automatically. If you believe that this
not correct, you can update the md5sum entry executing the following
command:
md5sum /etc/X11/xorg.conf | sudo tee /var/lib/x11/xorg.conf.md5sum
otherwise edit manually /etc/X11/xorg.conf to change the Driver section
from nv to nvidia.
zivs@zivs:~$

so i manually edited this "nv" to "nvidia". After that did a restart. And X window stopped responding - neither NVIDIA logo, neither xfce working - nothing. Below is the xorg.conf file how it looks when not X stops responding:
Section "Files"
FontPath "/usr/share/X11/fonts/misc"
FontPath "/usr/share/X11/fonts/cyrillic"
FontPath "/usr/share/X11/fonts/100dpi/:unscaled"
FontPath "/usr/share/X11/fonts/75dpi/:unscaled"
FontPath "/usr/share/X11/fonts/Type1"
FontPath "/usr/share/X11/fonts/100dpi"
FontPath "/usr/share/X11/fonts/75dpi"
# path to defoma fonts
FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
Load "i2c"
Load "bitmap"
Load "ddc"
Load "dri"
Load "extmod"
Load "freetype"
Load "glx"
Load "int10"
Load "type1"
Load "vbe"
EndSection

Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "CoreKeyboard"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "lv"
EndSection

Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
Option "CorePointer"
Option "Device" "/dev/input/mice"
Option "Protocol" "ExplorerPS/2"
Option "ZAxisMapping" "4 5"
Option "Emulate3Buttons" "true"
EndSection

Section "InputDevice"
Driver "wacom"
Identifier "stylus"
Option "Device" "/dev/wacom" # Change to
# /dev/input/event
# for USB
Option "Type" "stylus"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
Driver "wacom"
Identifier "eraser"
Option "Device" "/dev/wacom" # Change to
# /dev/input/event
# for USB
Option "Type" "eraser"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
Driver "wacom"
Identifier "cursor"
Option "Device" "/dev/wacom" # Change to
# /dev/input/event
# for USB
Option "Type" "cursor"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "Device"
Identifier "NVIDIA Corporation NV43 [GeForce 6600/GeForce 6600 GT]"
Driver "nvidia"
BusID "PCI:1:0:0"
EndSection

Section "Monitor"
Identifier "Generic Monitor"
Option "DPMS"
EndSection

Section "Screen"
Identifier "Default Screen"
Device "NVIDIA Corporation NV43 [GeForce 6600/GeForce 6600 GT]"
Monitor "Generic Monitor"
DefaultDepth 24
SubSection "Display"
Depth 1
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 4
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 15
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen"
InputDevice "Generic Keyboard"
InputDevice "Configured Mouse"
InputDevice "stylus" "SendCoreEvents"
InputDevice "cursor" "SendCoreEvents"
InputDevice "eraser" "SendCoreEvents"
EndSection

Section "DRI"
Mode 0666
EndSection
I've tried to comment out load "dri" but that didn't help.
Any suggestions/ideas?
thanks in advance

please show us the /var/log/Xorg.0.log file that accompanies these failures.

As I don't know which part is needed, i'll give a link to whole log file. Check here.

First of all, use the real nVidia driver, from
http://download.nvidia.com/XFree86/L...-8762-pkg1.run
then, as root:
./NV*
follow the prompts, let the installer fix up your config files, wait until it is all done, do:

apt-get install kdm
dpkg-reconfigure xserver-common

select kdm

dpkg-reconfigure xserver-xorg

make sure nvidia is the driver
uncheck the glx and dri modules
as long as you are here, make sure your monitor sync ranges are correct. Look on the specs for the monitor and find the horizontal and vertical sync ranges. Select advanced, when you get to monitor, and enter the sync ranges.
Finish the whole xserver configuration.
At the prompt:

kdm

and

The nvidia screen should show. Then X will work.