Suddenly, both my screen/tmux started changing my windows' names after every command. They keep changing the name to the value of $PROMPT_COMMAND on every single action on the terminal, even after manually renaming them (by Ctrl+A A on screen or Ctrl+B on tmux).
On tmux I already tried to change the tmux.conf settings to disable window auto renaming off, but seems that it was ignored.
I am using bash without the standard /etc/bashrc configuration file. My distro is Fedora 18.
Check whether your PS1 (plus PS2, PS3 or PS4 if those are set) is changing the title:
printf %q "$PS1" | grep -F '\\033'