Hi, I was getting similar problems with a laptop I have, but it was resolved a couple of radeon updates back.
Is this still a problem with the newer radeon driver from squeeze (also newer kernel and mesa)? (make sure you have libdrm-radeon1, firmware-linux-nonfree and firmware-linux installed). If problem persists, could you try getting the even newer one from sid (you'll need a newer kernel as well, either 2.6.32-10 from sid or 2.6.33 from experimental). For this you will need to enable Kernel modesetting. add *radeon* to /etc/modules and put *options radeon modeset=1* in /etc/modprobe.d/radeon-kms.conf (you'll probably need to create the file). What Desktop environment are you running? If gnome I recommend you don't do your dual screen setup in your xorg.conf file. If you specify enough virtual size as you've done, gnome should do it automatically for you (this is what happens with a couple of laptops I have). You can also simply use xrandr. Simply put the "right" command in a file in /etc/X11/Xsession.d/ (I assume this would work perfectly in KDE and others). This is a valuable resource: http://www.jejik.com/articles/2008/10/setting_up_dual_monitors_system-wide_with_xrandr_on_debian_lenny/ Hope this helps, Andres
