whole line echoed every char I type

[Dan Jacobson]

Holy moly, without LC_ALL=C, for every character I type, the whole
line is echoed!

03:39 ~$ LC_ALL=C script
Script started, file is typescript
03:39 ~$ exit
Script done, file is typescript
03:39 ~$ cat -v typescript
Script started on Tue Jan 24 03:39:46 2006
^[[01;35m03:39 ~$^[[00m exit^M

Script done on Tue Jan 24 03:39:50 2006
03:40 ~$ script
Script started, file is typescript
03:40 ~$ exit
Script done, file is typescript
03:40 ~$ cat -v typescript
Script started on M-&M-hM-$M-82006M-&~01M-$M-k24M-$M-i (M-6gM-$G) 
03M-.M-I40M-$M-@17M-,M-m
^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40
~$^[[00m e^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m
e^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m
ex^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m
ex^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m
exi^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m
exi^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m
exit^M^[[01;35m03:40 ~$^[[00m ^M^[[01;35m03:40 ~$^[[00m exit^M

Script done on M-&M-hM-$M-82006M-&~01M-$M-k24M-$M-i (M-6gM-$G) 
03M-.M-I40M-$M-@21M-,M-m

(One doesn't notice the echos. I broke the single long line above to
fit nicer in this message.)

BASH_VERSION='3.1.0(1)-release'
LANG=zh_TW.Big5
LC_COLLATE=C
LC_CTYPE=zh_TW.Big5
LC_MESSAGES=C
PROMPT_COMMAND=$'prompt_tricks_z=" $?"; prompt_tricks_z=${prompt_tricks_z# 0}\n 
case $PWD in $HOME) pwd=\\~;; *) pwd=${PWD##*/};; esac'
PS1='\[\e[01;35m\]\A$prompt_tricks_z $pwd\$\[\e[00m\] '