Installed Archlinux 32 and 64 bit (dual boot) with I946GZ onboard graphics

00:02.0 VGA compatible controller: Intel Corporation 82946GZ/GL Integrated Graphics Controller (rev 02)

Both oses work ok in the vt's and do use native resolution of wide LCD (with KMS enabled)

When i start kdm both oses display distorted background image (of kdm) in th LCD's native resolution, DONT display the actual login window, and mouse won't move

In the 64 bit system if i Alt Ctl F1 (to a vt) the display remains frozen on the kdm background, but the computer is responsive (e.g type 'init 6' and the computer reboots after few seconds etc)

In the 32 bit system the computer does not respond at all and appears frozen completely

If i disable KMS (add 'nomodeset' in grub) most stuff works fine except the display only supports 720x400 in the vt's and 1024x768 1280x1024 in the desktop, and does not support opengl (kde desktop effects work ok with xrender though)

You sound as if you know what you're doing.
I'll bet it's the X driver module, or the configuration thereof.

With KMS, try and find what X driver it finished up with in Xorg.0.log

I tried experimenting some more (though did not check the glxinfo yet)

kernel26 2.6.37.5-1
xorg-server 1.9.4.901-1
xf86-video-intel 2.14.0-3

Run kdm (login as root and /erc/rc.d/kdm start) :

kdm's background appears distorted [*1 below]. sometimes with mouse cursor and it's moving, sometimes without cursor. Except that the screen is frozen. Xorg.0.log is [*2 below]

When the display freezes it won't change anymore, but the computer "behind" is still responging. If i Alt Ctl F1 (to the vt where root is logged in) and run commands, PC responds :

ls -R / --> hard drive activity

killall X --> screen goes blank (and remains like that no matter what i do, even if i restart X) and the computer is stell responsive "behind" the blank screen

init 6 --> reboot after few seconds

ONCE EVER in one of the times when kdm mouse was movable I tab'd into the user password text fields (they appeared as soon as I began typing in them), logged in successfully, used the desktop for less then a minute and it froze dead. I tried to reproduce that and could not. Xorg.0.log from this time is [*3 below]



[*1]
http://www.picvalley.net/u/1526/143040026315454141841302352410MWmf3u8XerfrcvOFEdLk_m.JPG

[*2] http://pastebin.com/zxgY4qyj
[*3] http://pastebin.com/v1mHXeY6

I don't know archlinux. check the contents of /etc/X11 as some systems have bits like modprobe.d & profile.d.Slackware doesn't, btw so I don't know how they are set up.

Intel graphics seem congenitally knackered. I thought I was bad with ATI (And I was right). I would go on the supposition that the card is getting the wrong driver. Vesa? VGA? Newer driver? Patch?
Try Intel's and phoronix.com's forums.

If all else fails, I would run X -Configure, and set about xorg.conf. Try to get your graphics numerical pci id in there - there's some wheeze to do it. Check the driver sources to see if your pci id is covered (grep -r usually does that)