I have run into similar bug using Kubuntu 8.04.1 desktop CD. The installer disappeared without any warning and there was not /boot/grub/menu.lst on installed system. The stage files were present.

In installer log I have found the following errors:
Exception in KDE frontend (invoking crash handler):
Traceback (most recent call last):
  File "/usr/lib/ubiquity/bin/ubiquity", line 229, in <module>
    main()
  File "/usr/lib/ubiquity/bin/ubiquity", line 224, in main
    install(args[0])
  File "/usr/lib/ubiquity/bin/ubiquity", line 68, in install
    ret = wizard.run()
  File "/usr/lib/ubiquity/ubiquity/frontend/kde_ui.py", line 406, in run
    self.progress_loop()
  File "/usr/lib/ubiquity/ubiquity/frontend/kde_ui.py", line 708, in progress_loop
    (ret, realtb))
RuntimeError: Install failed with exit code 1
Traceback (most recent call last):
  File "/usr/share/ubiquity/install.py", line 1913, in <module>
    install.run()
  File "/usr/share/ubiquity/install.py", line 419, in run
    self.configure_bootloader()
  File "/usr/share/ubiquity/install.py", line 1422, in configure_bootloader
    "GrubInstaller failed with code %d" % ret)
InstallStepError: GrubInstaller failed with code 1

Traceback (most recent call last):
  File "/usr/lib/ubiquity/bin/ubiquity", line 229, in <module>
    main()
  File "/usr/lib/ubiquity/bin/ubiquity", line 224, in main
    install(args[0])
  File "/usr/lib/ubiquity/bin/ubiquity", line 68, in install
    ret = wizard.run()
  File "/usr/lib/ubiquity/ubiquity/frontend/kde_ui.py", line 406, in run
    self.progress_loop()
  File "/usr/lib/ubiquity/ubiquity/frontend/kde_ui.py", line 708, in progress_loop
    (ret, realtb))
RuntimeError: Install failed with exit code 1
Traceback (most recent call last):
  File "/usr/share/ubiquity/install.py", line 1913, in <module>
    install.run()
  File "/usr/share/ubiquity/install.py", line 419, in run
    self.configure_bootloader()
  File "/usr/share/ubiquity/install.py", line 1422, in configure_bootloader
    "GrubInstaller failed with code %d" % ret)
InstallStepError: GrubInstaller failed with code 1

I was trying to install to /dev/sdb1 and install GRUB into (hd1,0). 

Ubiquity version: Ubiquity 1.8.12

Here is output of fdisk -l for my system:
Disk /dev/sda: 640.1 GB, 640135028736 bytes
255 heads, 63 sectors/track, 77825 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1         608     4883728+  83  Linux
/dev/sda2             609        2432    14651280   83  Linux
/dev/sda4            2433       77825   605594272+   5  Extended
/dev/sda5            2433        2699     2144646   82  Linux swap / Solaris
/dev/sda6            2700        8778    48829536   8e  Linux LVM
/dev/sda7            8779       14857    48829536   8e  Linux LVM
/dev/sda8           14858       20936    48829536   8e  Linux LVM
/dev/sda9           20937       33094    97659103+  8e  Linux LVM
/dev/sda10          33095       45252    97659103+  8e  Linux LVM
/dev/sda11          45253       57410    97659103+  8e  Linux LVM
/dev/sda12          57411       69568    97659103+  8e  Linux LVM
/dev/sda13          69569       75647    48829536   8e  Linux LVM
/dev/sda14          75648       77825    17494753+  8e  Linux LVM

Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1         653     5245191   83  Linux
/dev/sdb2             654        1306     5245222+  83  Linux
/dev/sdb3            1307        1959     5245222+  83  Linux
/dev/sdb4            1960       30400   228452332+   5  Extended
/dev/sdb5            1960        2612     5245191   82  Linux swap / Solaris
/dev/sdb6            2613        5162    20482843+  83  Linux
/dev/sdb7            5163        7712    20482843+  83  Linux
/dev/sdb8            7713       10262    20482843+  83  Linux
/dev/sdb9           10263       12812    20482843+  83  Linux
/dev/sdb10          12813       15362    20482843+  83  Linux
/dev/sdb11          15363       17912    20482843+  83  Linux
/dev/sdb12          17913       20462    20482843+  83  Linux
/dev/sdb13          20463       23012    20482843+  83  Linux
/dev/sdb14          23013       25562    20482843+  83  Linux
/dev/sdb15          25563       30400    38861203+  83  Linux

I attach logs from installer.