Screen Resolution Won't Save -- please help

Windowx XP Pro Laptop
Dell Latitude D800 Pentium-M 512MB RAM

When the computer boots up, it always reverts back to a disply setting
of 1024x768. User wants it to be at 800x600 so I will adjust the
properties and it will stay that way until rebooted, when it will once
again revert back. When it first comes up, you can see it at 800x600
for less than a second, then the screen flickers and goes back to
1024x768.

I've already tried changing the registry setting listed at:

http://www.kellys-korner-xp.com/xp_tweaks.htm

to no avail. Any help would be greatly appreciated.

Ed