crashes w/ errors "partman exited with code 10", "RuntimeError: called outside of a mainloop at gtkui.py:1169 in watch_debconf_fd_helper, and more

I went through the 6.06 installer on my laptop. It went well but then after I clicked the start-installation button on the final screen it crashed. I think I had /dev/hda6 mounted on /dev/hda6, though I tried to unmount it through the GUI.

Ubuntu version: 6.06 LTS.

Errors in the log: "ubiquity: /bin/partman exited with code 10", "RuntimeError: called outside of a mainloop" at gtkui.py", line 1169, in watch_debconf_fd_helper, and more. For the full list of errors, see the attached log.

Settings I used: I chose French language and US keymap. I fiddled with the clock time settings for a while, and I set the time zone twice. I chose not to repartition or reformat anything. I set these mountpoints: /dev/hdc1 (FAT32) mounted to /m/w, /dev/hdc2 (FreeBSD FFS) mounted to /m/b, and /dev/hdc6 (ext3) mounted to /.

Hardware: 3-year old Dell Inspiron 1100 Intel 32-bit Celeron laptop.

Thanks for reading,
--Jason