GNU/Linux kernel 2.6
Slackware 12.0
KDE 3.5.7

Hi:
I've gone to Main menu>Control Center>Peripherals>Display>Size&Orientation>Screen Size and have lowered the resolution. But when I press the 'Apply' button, I'm taken back to the text console from where I ran startx where, as the first line, I can read 'startkde: Shutting down...'. If I reenter the GUI (run startx again) I see the resolution hasn't changed. What can possibly be the cause?

I've tried ctrl+alt++. This effectively zooms the screen in, but the screen gets larger than the physical screen.
Any suggestion will be welcome. Thanks for reading and regards.

I'm not that familiar with Slackware, but with some other distros I have had to change the resolution as root for it to be permanent (i.e. to last past an X restart).