The problem seems to be also that your grup-install target is a FAT
partition:
Nov 3 02:58:26 ubuntu 10freedos: debug: /dev/mmcblk0p1 is a FAT partition
(mounted by GRUB)
which later gives the
Nov 3 03:23:11 ubuntu plugininstall.py:
ubiquity.install_misc.InstallStepError: GrubInstaller
The drive that I tried to install on was a dual boot before (Ubuntu 32 bit
12.04, upgraded from 11.10 and Windows 7 NTFS). To my knowledge there was no
FAT partition on the /dev/sda1
As stated before I tried to to select /dev/sda1 explicitly when I tried to
install the first times. This bug
