Comment 3 for bug 164481

Hello,
i had the same problem using ubuntu 7.10. The installer stops at 15% an "detecting filesystems".
The log does not indicate anything interesting. However, i found an easy workaround.
In a terminal, check the device(s) associated with your external drive using df or mount. (at home, it was sdb1).
Then, unmount it using sudo umount /dev/sdb1
The installer is still blocked.
get the pid of 01unmount_busy. It should be the first in top then kill it.
the installer will re-ask you about the partionning.
This time, it will work.