Comment 4 for bug 272740

> jason@Kryten:~$ echo $PROMPT_COMMAND
>

Assuming you are running bash, then this is the issue. The title is set by the shell via an escape sequence, which is usually part of $PROMPT_COMMAND. For example:

cmsj@kodachi:~$ grep PROMPT_COMMAND .bashrc
    PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD/$HOME/~}\007"'