Created an attachment (id=27543)
Xorg.0.log from Gutsy (working)

Forwarding this bug from a Ubuntu reporter, Matthias Müller-Reineke:
https://bugs.edge.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/236006

[Problem]
System with i815 graphics fails to properly detect the monitor and thus provides only 800x600 resolution.  

This worked on the -intel driver back with xserver 1.3 and -intel 2.1.1 (Gutsy) providing 1280x1024, but regressed in Hardy and has been tested through Ubuntu Karmic Alpha-2.

[Original Report]
With upgrade to hardy the highest possible resolution reduced to 800x600.
In gutsy and dapper the highest resolution was 1280x1024@60 Hz on the same hardware.
The system was upgraded from dapper to hardy.
Chipset i815 (from Xorg.0.log)
Similar bug: #162136

in my GUTSY!-installation (for hardy with bug after reboot):

mueller@gutsy:~$ cat /etc/X11/xorg.conf
# xorg.conf (xorg 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 xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg

Section "Files"
EndSection

Section "InputDevice"
        Identifier "Generic Keyboard"
        Driver "kbd"
        Option "CoreKeyboard"
        Option "XkbRules" "xorg"
        Option "XkbModel" "pc105"
        Option "XkbLayout" "de"
        Option "XkbVariant" "nodeadkeys"
        Option "XkbOptions" "lv3:ralt_switch"
EndSection

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

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

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

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

Section "Device"
        Identifier "Intel Corporation 82815 CGC [Chipset Graphics Controller]"
        Driver "intel"
        BusID "PCI:0:2:0"
EndSection

Section "Monitor"
        Identifier "Standardbildschirm"
        Option "DPMS"
        HorizSync 28-64
        VertRefresh 43-60
EndSection

Section "Screen"
        Identifier "Default Screen"
        Device "Intel Corporation 82815 CGC [Chipset Graphics Controller]"
        Monitor "Standardbildschirm"
        DefaultDepth 24
        SubSection "Display"
                Modes "1280x1024"
        EndSubSection
EndSection

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

# Uncomment if you have a wacom tablet
# InputDevice "stylus" "SendCoreEvents"
# InputDevice "cursor" "SendCoreEvents"
# InputDevice "eraser" "SendCoreEvents"
EndSection

mueller@gutsy:~$ lspci -nn | grep VGA
00:02.0 VGA compatible controller [0300]: Intel Corporation 82815 Chipset Graphics Controller (CGC) [8086:1132] (rev 02)

mueller@gutsy:~$ sudo ddcprobe
vbe: VESA 3.0 detected.
oem: Intel(R) 810, Intel(R) 815 Chipset Video BIOS
vendor: Intel Corporation
product: Intel(R) 810, Intel(R) 815 Chipset Hardware Version 0.0
memory: 1024kb
memory: 4096kb
mode: 132x25 (text)
mode: 132x43 (text)
mode: 132x50 (text)
mode: 132x60 (text)
mode: 320x200x64k
mode: 640x400x256
mode: 640x480x256
mode: 640x480x32k
mode: 640x480x64k
mode: 640x480x16m
mode: 800x600x16
mode: 800x600x256
mode: 800x600x32k
mode: 800x600x64k
mode: 800x600x16m
mode: 1024x768x256
edid:
edidfail

# GUTSY (Good)
mueller@gutsy:~$ xrandr
Screen 0: minimum 640 x 480, current 1280 x 1024, maximum 1280 x 1024
default connected 1280x1024+0+0 0mm x 0mm
   1280x1024 60.0*
   1280x960 60.0
   1280x800 60.0
   1280x768 60.0
   1152x768 55.0
   1024x768 60.0
   800x600 60.0 56.0
   640x480 60.0