Comment 4 for bug 573618

The solution in this link ("sudo apt-get remove dmraid") worked for me, however the "nodmraid" boot option didn't (assuming I did it correctly).

At least one of the drives in the system has been used for RAID in the past which likely explains the cause. There is perhaps a problem though that previously the Alternative installers would detect this and ask you about it whereas the Desktop installers wouldn't look for it - the situation now seems to be that the Desktop CDs are silently ignoring anything they're confused about.