[edgy] Cannot choose refresh rate

I am running Edgy on a machine with i845GM chipset. I had different issues with resolution and refresh rate. Currently I cannot change the refresh rate of the monitor. It is constantly at 1024x768@75Hz. That was no problem as long as I had a CRT monitor. But now I have a TFT monitor, and it is blured because it must run at 60 Hz

Several times I tried 'sudo dpkg-reconfigure xserver-xorg'. The chipset and the monitor (Philips 150s) are recognized correctly and debconf complains nowhere, but my choice '1024x768@60Hz' is ignored afterwards.

DRI is enabled.

This is my current xorg.conf:

# /etc/X11/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 /etc/X11/xorg.conf manual page.
# (Type "man /etc/X11/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"
 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"
 FontPath "/usr/share/fonts/X11/misc"
 # path to defoma fonts
 FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
 Load "bitmap"
 Load "dbe"
 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" "de"
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 "Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device"
 Driver "i810"
 BusID "PCI:0:2:0"
EndSection

Section "Monitor"
 Identifier "Philips 150S"
 Option "DPMS"
 HorizSync 28-50
 VertRefresh 43-75
EndSection

Section "Screen"
 Identifier "Default Screen"
 Device "Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device"
 Monitor "Philips 150S"
 DefaultDepth 24
 SubSection "Display"
  Depth 1
  Modes "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 4
  Modes "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 8
  Modes "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 15
  Modes "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 16
  Modes "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 24
  Modes "1024x768" "800x600" "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