ubuntu install wizard crashes on migrating docs & settings

[Saser]

$ lsb_release -rd
Description: Ubuntu 10.04 LTS
Release: 10.04

I have 4 harddisks. sda sdd are ntfs and win xp is on sda1.
sdb sdc are ext4.
I plan to install Lucid in sdb & sdc like this:
sdb1:/boot
sdb2:swap
sdb3:/
sdc1:swap
sdc2:/home

When installing Lucid using the CD ubuntu-10.04-desktop-amd64,
I choosed not to format the partition / in the page of disk partitioning (the partition is formatted and has Kamic on it).
The page of docs & settings migration did not show up, and the wizard went directly to the summary page.
After I clicked install button, the install wizard crashed on about 80% when migrating the docs & settings,
and the installation totally failed.

But when I choosed to format the partition / in the page of disk partitioning (so I can not save the Kamic settings),
The page of docs & settings migration showed up, and I choosed not to migrate any Win accounts, and the installation can finished perfectly.

So it means that the page of docs & settings migration do not show up and the install wizard crashes unless you format the partition /, even it has been formatted before.