Installed Slack 10 from magazine discs. Screen resolution is only 800 x 600 and cannot be changed from Control Center. File /etc/X11/xorg.conf shows...

# DefaultDepth 8
# DefaultDepth 16
DefaultDepth 24
# DefaultDepth 32

# "1024x768" is also a conservative usable default resolution. If you
# have a better monitor, feel free to try resolutions such as
# "1152x864", "1280x1024", "1600x1200", and "1800x1400" (or whatever your
# card/monitor can produce)

Subsection "Display"
Depth 8
Modes "1024x768" "800x600" "640x480"
EndSubsection
Subsection "Display"
Depth 16
Modes "1024x768" "800x600" "640x480"
EndSubsection
Subsection "Display"
Depth 24
Modes "1024x768" "800x600" "640x480"
EndSubsection
Subsection "Display"
Depth 32
Modes "1024x768" "800x600" "640x480"
EndSubsection

EndSection

What am I doing wrong? Thanks.

In my xorg.conf there are lines "ViewPort 0 0" under each Modes lines ,like :

Subsection "Display"
Depth 8
Modes "1024x768" "800x600" "640x480"
ViewPort 0 0
EndSubsection
Subsection "Display"
Depth 16
Modes "1024x768" "800x600" "640x480"
ViewPort 0 0
...

I don't know if they are mandatory though...

That did it. Thanks.