Installer crash

I was running the Dapper Beta Installer, and I wanted to set up my 200 GB Maxtor with 50 gb for the root as ext3, 145 for media sharing between WinXP and Ubuntu(Dual-Boot) as fat32. When it tried to format partitions, the installer crashed and gave this traceback:

Traceback (most recent call last):
  File "/usr/lib/python2.4/site-packages/ubiquity/frontend/gtkui.py", line 1084, in watch_debconf_fd_helper
    return callback(source, debconf_condition)
  File "/usr/lib/python2.4/site-packages/ubiquity/filteredcommand.py", line 143, in process_input
    if not self.process_line():
  File "/usr/lib/python2.4/site-packages/ubiquity/filteredcommand.py", line 81, in process_line
    return self.dbfilter.process_line()
  File "/usr/lib/python2.4/site-packages/ubiquity/debconffilter.py", line 219, in process_line
    if not input_widgets[0].run(priority, question):
  File "/usr/lib/python2.4/site-packages/ubiquity/components/partman_commit.py", line 123, in run
    ('ubiquity/text/go_back', 'ubiquity/text/continue'))
  File "/usr/lib/python2.4/site-packages/ubiquity/frontend/gtkui.py", line 1463, in question_dialog
    dialog = gtk.Dialog(title, transient, gtk.DIALOG_MODAL, tuple(buttons))
RuntimeError: first member of each text/response id pair must be a string