Sorry, I missed where you said 8.04 works. Yes, there must be some problem in the Xorg or the Vesa driver for 8.10.
I'm afraid this is beyond my experience. You will have to wait for someone else for any real help. Ubuntu 8.04 is "LTS", it will apparently be supported for three years. Maybe you will decide to stick with 8.04 for a while instead :-).
I would not recommend trying to install the Xorg from 8.04. I guess it might work - but you will be fighting the package management system.
If you have time, you may be able to find out a little more for yourself. But it's a dark area. I make no guarantees, and I probably can't give you any more help.
1) Look at the differences between Xorg.log in 8.04 and 8.10. See if 8.04 does anything different in /etc/X11/xorg.conf. (If you do, please attach a copy of both files from 8.04).
2) Find out exactly what timings 8.04 uses. Run "xvidtune" from a terminal, and look at the output from clicking the "Show" button. The line of numbers is in the same format as the "ModeLine" directive as used in xorg.conf. (See "man xorg.conf" for details). Try entering this modeline into xorg.conf on Ubuntu 8.10. I'm *not* saying this will work, it just might make it clearer what the problem is.
Sorry, I missed where you said 8.04 works. Yes, there must be some problem in the Xorg or the Vesa driver for 8.10.
I'm afraid this is beyond my experience. You will have to wait for someone else for any real help. Ubuntu 8.04 is "LTS", it will apparently be supported for three years. Maybe you will decide to stick with 8.04 for a while instead :-).
I would not recommend trying to install the Xorg from 8.04. I guess it might work - but you will be fighting the package management system.
If you have time, you may be able to find out a little more for yourself. But it's a dark area. I make no guarantees, and I probably can't give you any more help.
1) Look at the differences between Xorg.log in 8.04 and 8.10. See if 8.04 does anything different in /etc/X11/xorg.conf. (If you do, please attach a copy of both files from 8.04).
2) Find out exactly what timings 8.04 uses. Run "xvidtune" from a terminal, and look at the output from clicking the "Show" button. The line of numbers is in the same format as the "ModeLine" directive as used in xorg.conf. (See "man xorg.conf" for details). Try entering this modeline into xorg.conf on Ubuntu 8.10. I'm *not* saying this will work, it just might make it clearer what the problem is.