How do I change screen resolution in SLES 8?
 

I have SuSE Linux Enterprise Server (SLES) 8 installed on my IBM Thinkpad T42.

When I go to Preferences .. Information .. X-Server, I see my screen resolution is set to 800 x 600.

How (from where) can I increase this?

Isn't SLES Yast-based, like all other SuSE's? Try Yast -> Hardware -> Graphics Card and Monitor. This will start sax2 and you should be able to change resolution.

It could also be a setting in /boot/grub/menu.lst that affects resolution. Try to change the vga= parameter according to this table:

When I launch Yast2 -> Hardware -> Graphics Card and Monitor. I get the following:
/sbin/yast2: line 149: 6271 Segmentation fault $ybindir/ysbase $module "$@" qt -geometry "$Y2_GEOMETRY" $FONT

When I launch Yast -> Hardware -> Graphics Card and Monitor. Nothing happens.

If I start Sax2 from the command line, the first message I get is:
"The Monitor couldn't be detected - Please setup your monitor manually. Do you want to start the configuration dialog to setup display now?"
I click Yes. I configure my monitor as an Model=IBM Thinkpad TFT. When I test this configuration, I get a black screen, so I undo my changes.

How do I resolve this?

I suggest to try a generic monitor first. Just pick one with an appropriate resolution from the LCD menu.

It could be also the graphics driver that does not support a higher resolution (maybe lack of video memory). Maybe you could provide more memory with the BIOS settings.

Check /var/log/XFree86.0.log and /var/log/SaX.log for more information.