Grub install failure on a MacBook Pro (Intel core)

Hi All,

I accidentally erased my OSX partition. Now there is only Windows XP on my harddrive. As I tried to install ubuntu on my MacBook, the crash occurred at the end of the installation process when the GRUB is to be installed.

Content of the crash dialog:

Traceback (most recent call last):
  File "/usr/bin/ubiquity", line 166, in ?
    main()
  File "/usr/bin/ubiquity", line 161, in main
    install(sys.argv[1])
  File "/usr/bin/ubiquity", line 57, in install
    ret = wizard.run()
  File "/usr/lib/ubiquity/ubiquity/frontend/gtkui.py", line 305, in run
    self.process_step()
  File "/usr/lib/ubiquity/ubiquity/frontend/gtkui.py", line 856, in process_step
    self.progress_loop()
  File "/usr/lib/ubiquity/ubiquity/frontend/gtkui.py", line 628, in progress_loop
    raise RuntimeError, ("Install failed with exit code %s\n%s" %
RuntimeError: Install failed with exit code 1
Traceback (most recent call last):
  File "/usr/share/ubiquity/install.py", line 1404, in ?
    install.run()
  File "/usr/share/ubiquity/install.py", line 385, in run
    self.configure_bootloader()
  File "/usr/share/ubiquity/install.py", line 1163, in configure_bootloader
    raise InstallStepError(
InstallStepError: GrubInstaller failed with code 1