My screen fonts under Ubuntu are occasionally completely screwed up. They show up in blue with overstrikes:

I think this happens when I reboot my machine without a second monitor being attached to it, which it usually has. I suppose X.org gets confused when it cannot find a monitor that used to be there.

To solve this problem you must reconfigure X.org. Just enter the following and log out and in again to your X session:

sudo dpkg-reconfigure xorg