I login with root. That is problem.
when i typed mount, i get this.
/dev/hda3 on / type ext3 (rw, errors=remount-ro)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
/dev/hda1 on /boot type ext2 (rw)