mount : according to mtab, procbususb is already mounted on /proc/bus/usb failed.

# cat /etc/mtab
/dev/hda1 / ext3 rw,errors=remount-ro 0 0
tmpfs /lib/init/rw tmpfs rw,nosuid,mode=0755 0 0
proc /proc proc rw,noexec,nosuid,nodev 0 0
sysfs /sys sysfs rw,noexec,nosuid,nodev 0 0
procbususb /proc/bus/usb usbfs rw 0 0
udev /dev tmpfs rw,mode=0755 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=620 0 0
shmfs /lib/init/rw/splashy tmpfs rw 0 0
/dev/hda6 /home ext3 rw 0 0
/dev/hda5 /tmp ext3 rw 0 0
/dev/hda3 /var ext3 rw 0 0