Input line of a terminal is messed and broken

[유병석(Byeongseok Yu)]

Configuration Information [Automatically generated, do not change]:
Machine: i386
OS: darwin11.3.0
Compiler: /usr/bin/clang
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='i386'
-DCONF_OSTYPE='darwin11.3.0' -DCONF_MACHTYPE='i386-apple-darwin11.3.0'
-DCONF_VENDOR='apple' -DLOCALEDIR='/opt/local/share/locale'
-DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -DMACOSX -I. -I. -I./include
-I./lib -I/opt/local/include -pipe -O2 -arch x86_64
uname output: Darwin yubyeongseog-ui-MacBook-Air.local 11.3.0 Darwin
Kernel Version 11.3.0: Thu Jan 12 18:47:41 PST 2012;
root:xnu-1699.24.23~1/RELEASE_X86_64 x86_64
Machine Type: i386-apple-darwin11.3.0

Bash Version: 4.2
Patch Level: 24
Release Status: release

Description:
Input line is messed and broken.

Repeat-By:
1. $export PS1=\e[34;40m[\u@\h \w]\e[m
2. #cd subfolders successively until PS1 echoes go over the half portion
of input line of a terminal screen width.
3. $ls <tab> # key to show up the file candidates.
4. You will see abnormal display - something like wrapping-around to the
beginning position

Fix:
[Description of how to fix the problem. If you don't know a
fix for the problem, don't include this section.]