No Mouse in X

I have reached a debian wall - I have been happy with my progress to date in getting my sarge built and running, but have run into something that I can't overcome.

The Problem:

When I run X (startx) from any user account, it begins, loads Gnome (just today downloaded it) but the mouse does not move. I found out that <Ctrl> <Alt> <Backspace> quits X, thankfully, so I can return to the command line.

My Analysis, such as it is:

I have run dpkg-reconfigure xserver-xfree86 many times to check the mouse settings, and everything looks fine. If I look at the file:

/etc/X11/XF86Config-4 it shows two entries for "mouse" one after the other as below...........................

# XF86Config-4 (XFree86 X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the XF86Config-4 manual page.
# (Type "man XF86Config-4" at the shell prompt.)
#
# This file is automatically updated on xserver-xfree86 package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xfree86
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following commands as root:
#
# cp /etc/X11/XF86Config-4 /etc/X11/XF86Config-4.custom
# md5sum /etc/X11/XF86Config-4 >/var/lib/xfree86/XF86Config-4.md5sum
# dpkg-reconfigure xserver-xfree86

Section "Files"
FontPath "unix/:7100" # local font server
# if the local font server has problems, we can fall back on these
FontPath "/usr/lib/X11/fonts/misc"
FontPath "/usr/lib/X11/fonts/cyrillic"
FontPath "/usr/lib/X11/fonts/100dpi/:unscaled"
FontPath "/usr/lib/X11/fonts/75dpi/:unscaled"
FontPath "/usr/lib/X11/fonts/Type1"
FontPath "/usr/lib/X11/fonts/CID"
FontPath "/usr/lib/X11/fonts/Speedo"
FontPath "/usr/lib/X11/fonts/100dpi"
FontPath "/usr/lib/X11/fonts/75dpi"
EndSection

Section "Module"
Load "GLcore"
Load "bitmap"
Load "dbe"
Load "ddc"
Load "dri"
Load "extmod"
Load "freetype"
Load "glx"
Load "int10"
Load "record"
Load "speedo"
Load "type1"
Load "vbe"
EndSection

Section "InputDevice"
Identifier "Generic Keyboard"
Driver "keyboard"
Option "CoreKeyboard"
Option "XkbRules" "xfree86"
Option "XkbModel" "pc104"
Option "XkbLayout" "us"
EndSection

Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
Option "CorePointer"
Option "Device" "/dev/psaux"
Option "Protocol" "PS/2"
Option "Emulate3Buttons" "true"
EndSection
Section "InputDevice"
Identifier "Generic Mouse"
Driver "mouse"
Option "SendCoreEvents" "true"
Option "Device" "/dev/input/mice"
Option "Protocol" "ImPS/2"
Option "Emulate3Buttons" "true"
EndSection

Section "Device"
Identifier "Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device"
Driver "i810"
VideoRam 65536
EndSection

Section "Monitor"
Identifier "IBM E74"
HorizSync 30-60
VertRefresh 50-75
Option "DPMS"
EndSection

Section "Screen"
Identifier "Default Screen"
Device "Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device"
Monitor "IBM E74"
DefaultDepth 16
SubSection "Display"
Depth 1
Modes "1024x768" "800x600"
EndSubSection
SubSection "Display"
Depth 4
Modes "1024x768" "800x600"
EndSubSection
SubSection "Display"
Depth 8
Modes "1024x768" "800x600"
EndSubSection
SubSection "Display"
Depth 15
Modes "1024x768" "800x600"
EndSubSection
SubSection "Display"
Depth 16
Modes "1024x768" "800x600"
EndSubSection
SubSection "Display"
Depth 24
Modes "1024x768" "800x600"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen"
InputDevice "Generic Keyboard"
InputDevice "Configured Mouse"
InputDevice "Generic Mouse"
EndSection

Section "DRI"
Mode 0666
EndSection

The mouse that I want is the first one, the "Configured" mouse. I must have caused the "Generic" mouse to appear somehow.

Now I have carefully edited the XF86Config-4 file, to remove the references to the "Generic" mouse, but still got no mouse response in X.

I am concerned that the text:

"If you have edited this file but would like it to be automatically updated
# again, run the following commands as root:
#
# cp /etc/X11/XF86Config-4 /etc/X11/XF86Config- 4.custom
# md5sum /etc/X11/XF86Config-4 >/var/lib/xfree86/XF86Config-4.md5sum
# dpkg-reconfigure xserver-xfree86"

is important, but don't know if it is significant. I did as it instructed, but ended up with the same file as before!

I have the file /var/log/XFree86.0.log available, but it is rather lengthy to post here right now.

I am very new to Debian, so please don't post "try this....." or "maybe that......" because I won't be able to follow. I have been scouring forums (there are so many!) and trying various "fixes" that were suggested, but might have made things worse by partial (or no) understanding! I guess I need quite explicit instructions on where to go (within Debian, preferably) and what to do.

Anybody willing to take this on????