Comment 24 for bug 197673

Heh, I should have read this bug before spamming the ubuntu-x mailing list.

Long story short: as acknowledged here, I managed to screw my only monitor (my laptop screen) via gnome-display-properties. It was even more serious, since I've just discovered that the offending file is .gnome2/montiors.xml (I somehow expected this to be in .gconf/)

By the way, a reinstall might *not* solve the problem. If you have a separate /home partition, and the user you create during the install is the same (same name, uid and gid) you had before (very likely in a home computer), you will still have the borked monitors.xml when you boot after install.