Xorg 6.8.2:can't swith to console from X

[giv <goldolphin@gmail.com>]

When in Xorg's GUI,I can't switch to virtual terminal by pressing ctrl
+alt+f1-f6,although there are 6 getty processes running.

I searched the web and got some information but couldn't resolve the
issue yet.

Also I can't switch the screen resolution by the "ctrl+alt+ +/-" combo
key,but "ctrl+alt+backspace" works.

I think it's the xkbmap that cause the problem,because I found some
hints in /var/log/Xorg.0.log:
    (EE) Couldn't load XKB keymap, falling back to pre-XKB keymap

and when I ran the following command:
    setxkbmap -rules xorg -model pc104 -layout us
it tells:
    Couldn't interpret _XKB_RULES_NAMES property
    Use defaults: rules - 'xorg' model - 'pc101' layout - 'us'
    Error loading new keyboard description

And,"setxkbmap -rules xorg -model pc101 -layout us" gave the same
information.There must be something wrong with XKB,but I don't know how
to resolve it.Can someone give me a few pointers? 

Thank you!

The keyborad section in my xorg.conf is:
Section "InputDevice"
        Identifier      "Generic Keyboard"
        Driver          "kbd"
        Option          "CoreKeyboard"
        Option          "XkbRules"      "xorg"
        Option          "XkbModel"      "pc104" #I have tried "pc105",no
improvement,either
        Option          "XkbLayout"     "us"
EndSection