• NEVER use sudo to start graphical programs. You should always use gksudo or kdesu to run such programs, otherwise new login attempts may fail. If this happens and at login an error message reports: "Unable to read ICE authority file", log in using the failsafe terminal and execute the command below substituting user for your username.

rm /home/user/.{ICE,X}authority

• To start a root shell (i.e. a command window where you can run root commands) use:

sudo -i

• To login as another user (on the command line, use something like gdmflexiserver for a graphical login)

sudo -i -u username