is it the grub in menu.list?
with xres=800x600 (boot code)
xrandr -s 800x600 doesn't change anything
xrandr -s 640x480 gives a bad screen
xrandr -s 320x240 gives a big screen
i read tdfx driver is good with libglide3
i don't know how to change tdfx driver by vesa driver

I thought I posted this already in this thread, but I guess I messed up some how with that. __{{emoticon}}__

Maybe you could try booting into init 3 by adding the number"3" to the end of the grub boot line.
Then log in as root:
Type: service slim stop (press enter)
Type: X -configure (press enter)
Note the capital X, this should make an xorg.conf in /root called xorg.conf.new.
Copy this to / etc/X11/ by
Type: cp /root/xorg.conf.new / etc/X11/xorg.conf (press enter)
Then try running slim to see if you have the correct screen setting.
Type: service slim start (press enter)
If you are still seeing a funny screen, you can specify the resolution using a mode line in / etc/X11/xorg.conf under the correct depth (or all of them)
I always use a mode line similar to:
Modes"1366x768"
In your case, this should be
Modes"800x600"
But you can also make a list like
Modes"800x600""1024x768""640x480"
This line should show up right under the
Depth #
Lines in you Screen section
Example: The resolution you would like to"force" should show up at the front of that line.
You can get back to the init 3 console by pressing"Control + Alt + F1"
Type: service slim stop (press enter)
Type: nano / etc/X11/xorg.conf (press enter)
Add/Change: Your mode lines
Press:"Control + x" followed by"y" to save
Type: service slim start (press enter)
If it is still not working right and you would like to try the vesa driver as stated above, you can edit your xorg.conf to use the vesa driver.
Press:"Control + Alt + f1" (press enter)
Type: service slim stop (press enter)
Type: nano / etc/X11/xorg.conf
In the Device section(s) change the
Driver *.*
Line to say
Driver vesa
Press:"Control + x" followed by"y" to save
Type: service slim start (press enter)

Hopefully this should get something working as it should.
Dave

In section"Monitor"
for Identifier"Monitor0"

i add
HorizSync 31-38
VertRefresh 60

Bingo. Wonderful
Thank's a lot