Are you using kdm or gdm?
If you're using gdm, then this sounds like a dupe of 118745, which was
addressed by hardcoding the dpi and should hopefully work with another
update.
If you're using kdm, then please use the displayconfig-restore.py script
in kde-guidance to fix it.
If neither of those
** Description changed:
Binary package hint: xserver-xorg-video-ati
After the last upgrade in gutsy, the dpi resolution is no longer
correctly recognized. Before the update xdpyinfo reported ca. 140x140
- dpi on my Dell Inspiron 8600 with 1920x1280 and an Radeon 9600 mobile
- resolution.
