KDM has a weird resolution

[the dsc]

I've just changed my monitor, whose resolution is 1024 * 768, as the previous one. But initially Kubuntu hasn't detected it, displaying 640 * 480. I could change trhough XFCE display settings, KDE wouldn't work for some reason.

Anyway, even though when I'm logged in KDE, XFCE or fluxbox, the resolution display is correct, KDM is weird. It has a "space" of 1024 * 768, but displaying under a 640 * 480 real resolution. Then I got to "roll" the screen with the mouse more or less as if I were browsing in a internet page that's wider than my resolution (but without the scroll bars).

Any idea on how to solve that?


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Solved already. It has to do with some configurations on xorg.conf. I could spot things like the smaller resolution and something like a virtual resolution somewhere, I've changed to the right resolution and now everything works fine.

[devils casper]

execute this

sudo dpkg-reconfigure xserver-xorg

accept default options and enter correct/supported HorizSync and VertRefresh rates when prompted. (Check Monitor's Manual for that).
Select supported Resolutions from List and reboot machine.